Finally got around to deal with the new frame, here it is minus the lid which I need to measure and order the parts.
V2 inside: Width 85cm & Length 80cm
V3 inside: Width 74cm & Length 72cm

The overall design is the same really but more compact. The difference here is that I can adjust the mount/scope up and down and back/forth inside the box.
This will allow me to find the optimal position.