The tear drop trailers are worth $$, they're considered classics if well-kept.
The biggest you could possibly go with a bumper tow would be 16ft. Even then you'd be pushing it. Bumpers are NOT made to tow travel trailers. A 16ft. TT, such as my 88' Layton, had a tongue weight of 440 lbs. Too much for our Ford Explorer bumper. It has a metal bumper with a max tow rate of 3500 lbs. Thats roughly 350 lbs in tongue weight maximum.
If you tow a trailer, no matter what size...do yourself a huge favor and buy a Class III or Class IV hitch and mount it to the tow vehicle.
Other questions you should ask before you buy a trailer...
Is your tow vehicle the right one for the job?
Does the travel trailer have electric brakes? (Most do, even single axle trailer..., you'll need to wire your tow vehicle to set up for electric brakes)
Tow vehicle: Are your brakes up to the task?
The very FIRST thing you should do is check the maximum tow rating of your bumper if you insist on being stupid enough to tow a trailer using a bumper. Its in the manual of the vehicle. Check the maximum tow rating for the vehicle, that information should be in the manual as well, or on a sticker inside the drivers side door.
