Pardon the humor and sarcasm...but you won't know if those leveling blocks are working without first purchasing an rv level! Our favorite is the T level which shows you side to side and back to front, all in one glance. It is very inexpensive and does a great job, in our opinions.
Of course, for extremely accurate leveling, there are many products to choose from and we will be certain to share them here as well. But we certainly like what we get for the money (a little over the cost of a gallon of gas) in the Camco 25543 RV T Level