Base Plate, under Ransom rest and windage base

I have a Ransom Rest I intend to start using in 2023.  I have the rest and the windage base.  I did not notice until recently that they offer a base plate for under that.  My previous recollection was that they encouraged shooters to build their own wood base, for clamping down.  
https://ransomrest.com/our-products/base-plate-master-series/

You recall correctly, their instructions have guidance on constructing your own from wood and plywood. Counterintuitively they suggest a platform bridged over boards at the front and rear.

I purchased the base, but it was too short to clamp the corners to the rigid base at my club.  That base is a drum that is half sunk in the ground, filled with concrete and topped with a steel pattern.  I ended up making a wood base that fits the plate.  I started clamping the corners.  However the steel plate was not flat so the wood base was not stable.  I ended up with three clamp pads under my wood base and three C clamps.

My message is, know what you will clamp to.

Yes they had a recommended size of 3/4" plywood with a 1/4" thick strip on the bottom at the front and rear. The size was like 12" X 14".(IIRC)
I have two pieces of 3/4"  plywood glued together with a 2" wide strip across front and rear. I used 2 thicknesses of plywood so I could use longer wood screws and not have them sticking through the plywood. I do not have the windage base