I bought a couple of these
https://www.homedepot.com/p/Everbil...Non-Marking-Rubber-Caster-4031245EB/203672395 I brought in the original leveling pegs to check the thread size. That was the hard part ... finding compatible thread size. Make sure you do the same.
Your observation on leveling is correct .... it left things a bit high on that side but I didn't screw them all the way in to check. I replaced the other wheels with 10in wheels from Harbor Freight. Overall it raised the grill a couple of inches. I didn't mind the extra height. On thinking about it now, perhaps I should have just placed a small block of wood under the original wheels. I like the convenience of being able to roll it around,
CampChef has a new frame that you change out with additional wheels but from what I remember, it's expensive and my wheel solution was cheap.