I have a slope both left-right and forward back. Consider my leveling job to be 2-stage...
I use a single block under each rear wheel to get the front-back closer to level (with final leveling done with the jack), plus I use two blocks under each right wheel to get side-to-side leveling. Doing both of these things should be fine on the suspension, since front-back and side-side are each done evenly.
The first time I parked it here, I didn't do the front-back leveling with blocks. I just used the jack. What I found was that I had to lower the jack enough that I was worried about putting too much stress on the front axle. When I checked the wheel lugnuts, I found that I had taken so much weight off the rear wheels that I could spin them when torquing the lugnuts.
2013 Escape 19 ("The Dog House") , 2012 Nissan Frontier