With a high mileage tug I personally would check The rear brakes
, fronts are usually better maintained since they do most of the stopping in daily operation, lube/ check the drive shaft, by 100,000 miles the u-joints have done their time. This applies to sealed rear axle
bearings too. When these items fail on the highway you will hear a grumbly noise and then a disasterious bang, not much interval between the 2. Raise the rear tire pressure for the load incountered when you tow. If your rear tires
are not showing any weird wear patterns the shocks are probably OK. Warn shocks usually show up when the cars is lightly loaded instead of heavily loaded. Any loose or squirly steering issues will be worse with the trailer load on the back. If you dont feel comfortable with your Blazer to hop in and drive cross country it would probably be prudent to have a good established mechanic put it on the rack and give it the once over. it will cost you some coin but you will sleep beter.
Of course you will have to deal with the Tow hitch and brake controller and trailer wiring hook-up.