Bottom of the anvil has 4 holes and one big one in the center (i believe it's 3/8). You could easily use the center hole to mount the anvil to the tripod, but there is a big possibility that it'll come loose under torque of movement of the rifle on the anvil.
If the anvil is secured by the 4 smaller bolts, you're eliminating the change of that.
I got the plate from @midwestoffroad and it works perfectly for the application between anvil and rt90c
If the anvil is secured by the 4 smaller bolts, you're eliminating the change of that.
I got the plate from @midwestoffroad and it works perfectly for the application between anvil and rt90c