I currently have 3 bags of Legos. I use about 3 or 4 on the tongue jack. I've never needed more than 3 bags. Although, I passed a few sites last week that people had about 4 high on one side. I try not to stack that high. But, you will need a bunch if you own a tandem axle TT due to multi-level stacking or both wheels. Can't imagine doing it with a class C.
2013 Jayco Eagle 328 RLTS
2012 Ford F250 6.2L 4x4 CCSB W/Air Lift air bags
2002 Coleman Bayside Elite (traded)
Me, Momma and Charles (RIP buddy)
And introducing Sofie!! ;)