Irrespective of what the tow bar has been hitching, I would not by a wagon with 160,000km on it unless I had a very good idea of how it had been used by way of driving, never mind what it was towing. Daily grinding city traffic, absolutely no-go. Daily long-distance driving, yes. Most people get rid of their cars between 160,000 and 250,000km, mostly for increasing repair costs and plain wear and tear, and some wagons I looked at before landing my SV6 were OK inside (2 with cigarette ash holes in the carpet), but had missing services. Look for one that has about 40-50,000km of sensible driving with full service history. City driving, even if it looks cool, is not sensible for these cars, and craps the engine with carbon, something the SIDI engines are known for, but you can easily deal with it by driving long and fast frequently and using premium unleaded (steer well away from E10/E85).
The auto transmission service is at 100,000km intervals, and should have been done to log-book servicing schedule by the previous owner if at/over 160,000km. All services must be logged, including the transmission, coolant, oil changes and A/C refresh, plus filters.
The tow bar is an option on the VF SV6 (e.g. Sportwagon) wagons, with plug-and-play wiring tunnelled beneath and behind the diffuser to the left hand side panel where the fuse box and battery/wiring harness is. Tow bar installation is about $1,000 on the SV6 (not DIY!). Once in place, clearance is "programmed" into the MyLink interface so that the radar pods at the rear allow extra margin when manouvering (especially for park assist, where the wagon can reverse-parallel park itself and needs the clearance without a tow bar). When the tow bar is not in use, remove it.