I have made a similar front wooden jacking piece as you Dave. I also get some jack clearance issues but planed the wood to allow enough clearance.I used a double thickness of wood with 2 x 1 strips on the top for location. One layer of wood id ply - cut from some offcuts kept for just such a use - always handy to keep.
I put 4 small strips of wood under it to locate it on the jack's round swivel.
Your second version for the rear looks a good one too.....
I am also looking to make something to raise the jack so that the car can be raised higher. Use on floor and put stands in - slide a raised base under jack and raise further... or similar.
This is to get the car raised higher to give more room underneath. If the car gets to too steep an angle then intermediate raising of the rear should solve that.
But then.... would it be easier to buy a pro system that raises the car in one go.
Expensive but easier.
