I can't get to ebay to look at the one you're interested in, but I recently bought an enclosed trailer myself.
I think you're looking at the best all around size. I tried out an 18' and it was tight and left little room for any extras. 24' was really nice, but it was getting to be a little more than I wanted to tow and stow. I found the 20' to be just about perfect for the Viper. If you dont have any concern about towing or stowing the 24', go for it, but the 4' is more than I wanted to deal with since the 20' met my needs.
I would advise getting aluminum wheels and a spare. Those POS white wagon wheels that come std on most of these things tend to rust out fairly quickly, plus the aluminum look way better. Many builders use the cheapest components, including tires, so get that spare!
I went with black exterior to match my truck. Looks sharp, but I was concerned with the heat. The top is silver (aluminum), not black, so it's not as hot as I feared it would be. In hindsight, I'm glad I went with black.
Most of the other options can probably wait or be installed later by yourself after you've spent some time with the rig and have a better feel for what you want or need.
One thing I did with mine was paint the wood walls white and the floor gray (with non-slip). This really brightens things up inside the trailer, plus it looks more finished. Cost about $50 and a couple of hours of labor, but well worth the time.
In the future I'm going to make a tire rack and add a winch in the front.
Also, as I just mentioned in another thread, check out the used trailers within a 200 mile radius... I found some very lightly used trailers for about 50 to 75 cents on the dollar. The tough part is finding exactly what you want, but if you find one you might save some significant money.
Good luck with your search!
