For easy side-to-side leveling, take a look at the RVPillo...
RV Pillo Leveler - Tandem Wheel  - $295.00 : RVPillo.com
We've used ours about a dozen time now, and really like the ease of use...it's a rugged, multi ply, 'bag' that's lots easier than 'legos' or blocks of wood...a bit more pricy, however, but much quicker and safer IMHO!
1.place your AS where you want it sit
2.place the RVPillo next to the wheels on the 'low' side
3.pull AS forward just enough to slide the RVPillo in the space where the wheels were previously
4.back AS onto RVPillo
5.fill RVPillo with air till trailer is level, side-to-side...
I use a small 12 volt
air compressor that I always carry - comes in handy for many uses when you need it!