Sikoriko, never had the need to level my 31 foot Class C with blocks. We mostly stay in provincial campgrounds, Alberta and BC. For the most part, they're graded very well. In some boondocking sites, I just eyeball the ground and move the RV as needed. Wife and toddlers never complained about how level it was, just the bounce during the middle of the night if someone has to get up.
Purchased the jack stands at walmart today. I'll try them out this weekend and let you know.