FYI, the instructions for the 465 RAP list a minimum spring length which was exactly the length mine was with full pre load. The adjustment nut next to the RAP housing should still have some room to be adjusted. The adjustment nut sets the primary sag and the RAP unit is considered the fine tuning. If you have room to raise the nut 5mm up on the threaded housing, it should net you approximately the 10mm of sag you are not getting now. Basically, you follow the instructions for the non RAP model to get it close. The RAP housing is not threaded onto the shock body but just slips over it. The spring tension may make the RAP housing turn when you try to adjust the nut higher up on the housing and if this happens, it is recommended to remove the shock to make the coarse adjustment.
With this said, I had the opposite problem and am not a suspension expert. I had a lot of learning to do getting mine set up. Just remember that in no way should the spring sit loose on the shock. If you adjust the adjustment nut to have less preload on the spring, make sure that at full extension, the spring is still securely held in place. I seriously doubt that a 5mm adjustment at the shock body would loosen it that much but just be aware.
Once you get your sag set, don't forget that you have 5 rebound dampening adjustments that can be made. #1 allows the shock to rebound the fastest and #5 makes it rebound the slowest. If the bike feels like it wallows in corners or springs you up (pogo like) after a bump, it is set on too low a number. If you were to ride over stutter bumps and the ride gets harsh, it is set on too high a number. You can find a happy medium but learning what number setting works better on the different types of roads you ride will make your ride nicer! Also remember not to adjust the rebound from 1 backwards to 5 or from 5 straight to 1. Always go up from #1 and down from #5.
2002 BMW K1200LT
Some people just don't get how a 300+ mile round trip for lunch makes sense.
If you are reading this, you probably do.