Have you looked at Jayco Seismics? I've got the 3912. Has a 12ft garage, but not sure the exact measurement. Ours is a 44 footer, but they have smaller models. I love the quality of Jayco. I looked at all the other brands, read reviews, etc. But, I was convinced by just plain word of mouth. Every Jayco owner I met, is happy and only recommended one.
When it comes to your tow vehicle, be very careful. These toy haulers are heavy girls. I had a Dodge 2500 which I modified with air bags and an exhaust brake. This truck did just fine in OK, AR, and TN. But, I burned up the tranny in CO, pulling up Monarch pass. I now have a Dodge 5500 and it pulls like a dream. If you will be pulling in mountainous areas, you'll need low gears. My 5.9 Cummins in the 2500 had the power, but the tranny didn't make it. My 5500 has 4.88 gears. It pull my rig anywhere.