After 30 plus years of towing travel trailers we did put an airbag set up in the back. Had airshocks up until then. For other reasons I clipped the front end but it did help having disc brakes up front. But did go 15 years with the standard brakes and had no issues, as all of my trailers have had their own brakes to supplement the car brakes. A quality weight dristribution trailer hitch with antisway device is critical. Other than that, wagons were made for towing. Most of them, and all the bigger old ones in particular. Happy trailering
Towing RV's------------- The type of vehicle really doesn't matter until you get into very long heavy trailers and larger tow trucks. ---As for typical station wagons, the following should be okay. ---We've only had one wagon for RV towing, a 1972 Gran Torino. With it, all pick up trucks and vans, I added an electric brake controler for the trailer brakes, a fairly large tranny cooler in front of radiator, and air shocks. Add air for trailer towing. Remove some for regular driving. Like mentioned a quality hitch with equalizer should be considered for anything larger than 20 feet. Many small Shasta and Airstream Bambi type trailers tow well with a simple ball hitch. Also the older small type RV's did not have electric brakes. In the good ole days most hitches were nothing more than a ball mount attached with clamps to the bumper. Still, overkill with a good anti-sway load leveling hitch is the way to go. Found out the most important item is that extra tranny cooler. Bypass the radiator cooler also. My first tranny cooler was an old house refridgerator cooler. Used it on many vehicles including my Chevy van. Also use quality highpressure fluid lines.
I used to tow with my 90 Pontiac 6000 3.1 V6 wagon all the time. It had an SE suspension that extremely stiff. It also had the ELC air ride, which was a constant headache and when it didn't work it didn't hold the car up even under its own weight, so I put Trans Sport van springs in the back. I had a 4x8 enclosed trailer I built, then later a Haulmark 5x8 enclosed that I still have. Maybe something with the airflow, but it actually towed the Haulmark better on the highway than my 3800 Trans Sport van does. And got better mileage. I also have a boxy 16 ft Sunline travel trailer that I towed with the 6000 quite a few times. It towed it with great stability, but the 3.1 was just a little underpowered trying to pull the big box through the wind. A rounder trailer would not have been a problem. It was also nearly impossible to see around even with extension mirrors because the wagon is narrower than the van, I would have needed some huge extension mirrors. On both trailers I designed a custom disc brake setup and use Carlisle Hydrastar actuators. I got both actuators really cheap. I use a Tekonsha Envoy controller which is proportional and easily adjustable. I put a transmission cooler on both vehicles and from what I have heard, transmission heat is the worst enemy when towing. Trailer hitches seem to come with these little clip nuts that you're supposed to put in the frame/unibody. That just looks too chintzy to me. I use a length of angle iron and heavy bolts to back my hitches. I also use a weight distributing hitch for the camper. This camper is built really well and I load it with the proper balance, it doesn't sway even if I try, so I don't have sway control. I've been through fierce Michigan windstorms with no problems. But I know some aren't designed that well, and longer trailers can more easily sway anyway.
Ooop! I forgot about the clamp on trailer mirrors. Mirrors can be a problem with a nice paint job if not the right type or mounted properly. You do need to see what's back there. Thanks for mentioning the mirrors. You need them when passing, changing lanes at 100 MPH, and when backing into that perfect campsite. You know, the one with the water spigot, electric box, and that small tree that all seem to pop up as you are backing in between the other large trees, shrubs, and campers.
1951 21' and now I've added a 1960 24', both Airstreams most recently. Have towed the large 17' Boler, several other 17' travel trailers, a car trailer with cars on it of various sizes/weights. Of them all the Airstreams (old ones as I've not towed a newer one so can't say) tow far better. The round shape does make a noticeable difference. The Boler is close to the same shape with rounder than most trailer corners and it also towed very well. The tranny cooler was a good suggestion and one I'd forgotten to mention. It is almost mandatory to ensure your transmission survives. If your wagon came from the factory with the tow option it may already have this. If the dealer installed the hitch, it may not. Until the mid seventies most trailers, of all sizes, were towed with cars and generally that meant wagons. And few of those had disc brakes. The world has changed a bunch since then with regards to speeds and freeways, but still, with yours being an 89 it likely has disc brakes up front, superior braking to anything from the 70's and older regardless of make. Then the manufacturers started to make trucks more pleasureable as long distance comfort machines and they quickly replaced wagons as the hauler of choice.
Very little help here. But try some of those vintage RV sites. Sorry don't have addresses. Possibly begin with "Tin Can Tourists". Possibly they haven't changed over the years and later mirrors will work.
Search Craigs List and Kijjiji for McKesh Mirrors. Don't buy them new - way too much money. But used you can often find them for under 50 bucks, we often find them at swap meets for 20 and less. About the best trailer towing mirror on the market for vintage tow vehicles.