If your goal is small storage, and inverter, it's a nice neat package. For a TT though consider, for less than $225 you can get a pair of GC-2 batteries, and another $100 will get you a larger PSW inverter for running AC powered items.
The 400 model listed on their site has a 33 Amphr battery (Lion)
and a 300 PSW inverter. (enough to run a tv, or to power small appliances or lights. for $449.
Spending less on bigger batteries on the TT, GC-2 could give (200 amphr), with a 500 inverter, would in a pinch even allow you to run an extension cord into your home from the trailer (if you can park close) and power something like your refrigerator in a pinch. You would even have money left over to get a solar panel and small controller.
If compact and a clean little unit is your goal, go for it, if you want maximum bang for your buck, use the sysyems as are common on a TT.
JMHO