There are 12' separate garage bumper pull toy haulers out there if that is what you are looking for? Pacific coachworks has a 30' BP toy hauler with a 12' separate garage:
http://www.pacificcoachworks.com/products/sandsport-300fsg/ I have never seen one with a larger separate garage than 12' in a BP. Also, be sure to measure the garage b/c sometimes it is not actually 12' instead like 11' 10" etc. Those are heavy sob's for a bumper pull also?
2005 Dodge 2500 5.9 SRW long bed
2014 FS28 Evergreen Amped TH Blue Ox 2000# WDH
2300CC VW turbo 4 seat sandrail, Yz450f, 350 Raptor quad