Adequate tow vehicles - rule of thumb?

I'm a prospective TrailManor buyer, with a questionable tow vehicle at the moment. I joined another thread with a question about using a Jeep Liberty as a TV. You were all very kind to contribute your opinions. Today I see that the Liberty has again surfaced in a thread about Toyota Highlander Hybrids.

Most of the comments I have seen from TM owners using Jeep Liberty as a TV (usually towing a 2720) have been positive. At least one-from someone who seems to know what he's talking about-says that it's an accident waiting to happen.

My question is: is there a rule of thumb to indicate what specs a tow vehicle should have in order to safely and adequately tow a trailer of a given size? For example, it was said that the Liberty's wheelbase is too short to tow a 3124 and borderline for a 2720. Okay, how would I know what wheelbase would be better suited for a 3124? I also heard that the Jeep's power is too weak to tow a TM in the Rockies. How much HP would be adequate?

How can I know how to select my next vehicle? Most of us have to balance the tow vehicle trait with whatever else we use that vehicle for. We wouldn't want the biggest, baddest gas guzzling pickup truck for our daily commute to work. But we might need the biggest, baddest gas guzzling pickup truck to pull a fifth wheel trailer. Somewhere between the BBGGPU and the Liberty is a collection of vehicles that are safe and adequate for the TrailManor without being excessively expensive to buy or operate. How can I identify them?