ONe of these days you're bound to encounter a parking spot where you'll have to put the tongue virtually on the ground to get level! A good solid chunk of wood works great but I've been using twelve 5/16" thick, 8 x 10 hard plastic cutting boards that I bought at WalMart for about $1.99 each. I stack them for levelling, in moderate situations, and place one under each stabilizer jack almost every time I set up. For Winter storage on my drive I place one under each tire, one under each stabilizer, and one under the tongue jack. My storage pad is asphalt and, no matter what you do, the weight of the AS will cause depressions --- generally at the tires since the stabilizers are not loaded that heavily.
2003 GMC 3500 D/A, CC, LB, 4x4 and 2000 Airstream Excella 30. WBCCI 7074