First off, yes having your vehicle and trailer at the event should be no problem and is pretty common at many STAR and even regional events. Some times trailer parking is off site, sometimes its in the hotel lot. In almost all cases having your tow vehicle and bikes at the hotel is done.
I would start with talking to the folks at the hotel. When I called to register I asked about leaving a vehicle (and trailer but not bikes) there while we took off riding for a week or so. I explained we would be back for another night stay before we leave. (That always seems to help when I or others I've talked to have done this, more revenue for them later gives them incentive to agree.) We do still plan to do this, if not we'll be looking at other options. I plan to talk to them again when I arrive and make sure we iron out any details.
I've done this twice for STAR, in Taos NM in 2010, and in Avon CO for 2012. (Avon is a bit of a special case as we've been at that site many times and a former member used to be the manager so we get treated well.)
It is not uncommon when a rally is out west for a few people do do something like this (leaving tow vehicle and trailer behind). I'm not sure if the club has ever worked out much of this in advance other than trailer storage during the event.
PS I am speaking from personal experience, not gauranteeing anything or speaking for the club agreement with our host hotel.
