Tom,
There have been many inovations to making the conversion to the RMG on a boat that is already decked. Most have worked fine. Cameron Hunt of the Piedmont group recently built a new boat and installed an equipment board system with a boom like extension into the bow for the turning block. The system comes out as one unit.
There has been a move in the last couple of years to these systems. One or two were also built in Stowe las winter. The interest is mainly to install a bow turning block mount that is accessable and thereby head off possible failure trauma of a failed hard mount at station 4.
Whereas, you are starting anew with the sheeting system, you might contact him for further information. I am sure you know him.
Rick