RGs come in two styles. The most common one is with a top-routed control cavity with the pots and switch mounted to the pickguard. The other is with a rear routed control cavity with the pots and switch mounted to the wood and a pickguard with big cut-outs that fit over the knobs and switch. Your pickguard is for the former style, whilst I've got an RG with the latter style.
I'd suggest that you think about getting a similar style pickguard made to better match the guitar.
With your current pickguard, the extra depth created by the guard means that the pot shanks and switch screws are unlikely to be long enough to fit. Also, the switch slot will need to be lengthened slightly at each end to allow the switch full travel (and in positions 1 and 5, the knob might prevent the switch from travelling fully if it's shaft is on the short side).
As Waz said, PM Pablopepper and he could make you a custom scratch plate. You might need to trace/shade the cavities on a piece of paper and send it to him in order to get the dimensions correct. The real problem is the curve of the guitar body. You'd want a really thin flexible guard in order to curve it well, but that would mean a less secure mount for the pickups. You/Pabs might be able to glue another layer under the guard in just the pickup area in order to provide some re-enforcement.