When we had our HTT, which was approx. 23' when towed, but approx. 30' when opened up, I always said 30'. Now that we've changed to our TT, which is 26'+ box, and 29' bumper to ball, I still say 30'. Generally speaking, it's not going to make any difference in cost for your site, they just don't want to try to cram a 32' TT into a 20' site. If you're lucky, you can look at sites online and pick one that suits you. With the HTT, we had to make sure there wasn't a huge tree that would be in the way of dropping the rear bunkend. Now with the TT, it has a deeper slide, so we need flex space to shift to the right a bit more. If you have a deep slide, but sure to mention that. Also the location of the power & water can make a difference. Agree that making sure you can park you tow vehicle in the site or at least next to it is important, so check that.