rufstuf

I have a 97 993 2S with 17 in. wheels. I recently got a great deal on a set of 18 in. Champion RG5. Front wheels fit fine; however, rear wheels will need new spacers to fit properly. My RG5 rear wheels are 18x10 and have a 58mm offset. I would like to change out the 31mm adapter for a 21mm for proper fit. However, the problem is that the rear wheels do not have the cavities where the wheel sit against the hub. It is flat and solid. As a result, I have not been able to locate any adapter in the width that I need where the lug nuts once installed will be flushed to allow the RG5 to sit flush. An option that I have explored is replacing the studs with longer ones and use spacer instead of an adapter with pressed in stud. However, this route will be more trouble, meaning more time and $$ to install. Hubs need to be removed, old studs replace, and bearings replace as well. Before I do down this path, I would like to know if this is the only option or are there others. Have anyone done this before? Any suggestions will be greatly appreciated.