Nice grow. Ive thought about doing it the same way. Id just be worried about theft; anyone with a truck and hitch could make it disappear. Ive been watching the prices on security cameras lately, they are getting very affordable. Also, will frequent traffic into and out of a trailer claimed to be for storage raise suspicions? If somebody pulls into the driveway to turn around, will they smell it? Hear fans/buzzing? or the mail guy, or UPS guy, or pizza guy, or a friend/relative, etc. Other than security, (which is a concern not to take lightly) its pretty good.
PS i added a dehumidifier, i would recommend it, i added a very very small one and my humidity stays low.