First and foremost, do NOT use cinder blocks!
They are way too unstable and brittle.
The levelers on the trailer should be sufficient. You can add some jack stands if you want.
And second, there is no reason to lift the trailer that high. You are just giving yourself a very tall first step and allowing more wind and water to get under the trailer. I see no advantage to lifting it that high. You could take the wheels off for storage, but again, no reason to keep it that high.
2013 Winnebago 2301BH-Red
2012 Ram 2500 Megacab HO CTD