You should be able to go to the local DMV with the signed Bill of Sale w/VIN number--this should be enough to get a temp permit to take it home, or go by that office prior to the sale and see what they need to issue the temp permit.
Then, if the seller has no lien on the trailer, he should be able to sign it in correct space and you can use it at your home DMV to apply for title and pay taxes. Having the Bill of Sale notarized may help in getting the new title.
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired