I have been parked where there was a huge slope and the shim capability was good.
The plastic I have come to detest as they will allow things to 'slide'... which can be a good feature... but, not when you want stability... important on the tongue jack...
So, a rule of thumb... I put a 3/4 plywood 'base' to spread the 'load' and keep rocks from damaging the underside of the plastic legos... It is amazing how much easier the Airstream tires seem to 'climb' the wooden blocks... without 'skidding' the plastic blocks which can be a nuisance when trying to set multiple under our 3 axle dainty AS.
If you get some 'sliding' of the wood sheets, a couple of flat head sheet metal screws, one on each corner, will keep things from sliding. Also, you can cut a 45 degree on the leading edge of the board and line them up for a 'ramp'..
Also, the 'stabilizers' tend to move a bit on the plastic legos...so the camper rocks more on them than on a wood base.
Sometimes 'wood' is the best solution for the problem..... depends on your use of your AS.... enjoy.
Peace and Blessings..