4 is better than 2, for sure. If you are mounting them permanently, I would only mount the rear 2 permanently and make the front 2 removable, cuz 8" is too close for comfort IMO. If you are going to make all removable, IMO you should still use 4 because 2 really won't do much if the only other supports are tires.
On my 5er I have front legs, rear stabilizers and then I added 2 scissor jacks in front of the wheels for a total of 6 landing points and it's pretty much rock solid.
2012 Eagle Super Lite HT 26.5RKS
2005 GMC 2500 SLT HD D/A