Staying with the Powerlite brand you could go with the 22CBX and have plenty of room without any cabinetry being in your way. both bikes could load next to each other but I would still stagger 12". Should still fit into state parks..
http://www.pacificcoachworks.com/products/powerlite-22cbx/Check out Condor wheel chocks. I use the free standing with floor mount bracket. I use the free standing because I can take it out of the traielr and use it in the garage or a cargo trailer if need be..
The condor will allow you ro ride in right next to the wall within a couple of inches and lock in and get off the bike. You then can tye the bikes down. I use ETrac on the floor. 10' sections on each side and one down the middle...
http://www.amazon.com/Condor-Pit-Stop-TrailerStop-PS-1500/dp/B001AWLJG6/ref=sr_1_1/189-7927894-7258250?ie=UTF8&qid=1429199646&sr=8-1&keywords=condor+chocks
