We used to own a 30 foot, 1996 MH with the 454CID fuel injected motor and we towed a Jeep Cherokee all over the west without any problems. We did add a Banks exhaust system and the performance was greatly improved. The rig never overheated, but we also added some DIY air dams to prevent incoming air from escaping and thereby pushing more of it through the radiator.
The biggerst problem with this MH was that it was on the P30 chassis and only had a 190" wheelbase. This chassis had a narrow front track and independent front suspension. We added about $1800 of after market suspension upgrades (trac bar, Safe-T- Plus, Bilstein shocks, etc.) and the handling was much better.
The MH you are looking at will probably have a longer wheelbase and may be on the P32 chassis which has a wider front track. And, with the addition of a Banks or other performance exhaust system, it should be fine.