All touring bikes include clearly explained weight capacities so you're looking at non-touring bikes?
I wouldn't buy a bike on the Net but I'd do some careful research online. You really want to get your touring bike from and assembled by a bike shop.
david boise ID
My experience towing a BOB trailer with my Paramount critereum bike is that I found it to be so scary, I never ever did it again. If you want to tow a BOB trailer, you need a longer wheel base.
As for weight specs...
Most commercially available touring bikes are light touring bikes. This means credit card touring. The frame probably won't immediately break if you put rider and gear on it, but it may wiggle. I did not like riding a wiggling frame, although it was excellent active feedback for quieting my upper body movement.
This is why they sell heavy touring bikes: Bruce Gordon, Waterford, Co-Motion, just to name a few.
So how can you figure out what to buy? I don't think you can do this over the Internet, unless you know what you are doing. You have to work through you local bike shop, and that means getting a local bike shop that you trust. I am not saying this is easy, because not too many bike shops have someone on staff that tours. And you have to have a local bike shop that you trust to fit the bike properly to you.
Perhaps the original question should have been "I am looking for a bike for a cross country trip, are there any recommendations?"