This company, Clips and Fasteners.com, also has a wide variety of well nuts, like the ones used to hole windshields on our fairings.
http://www.clipsandfasteners.com/Nuts_Well_s/138.htm
Thread: #10-32
Head Diameter: .750"
Overall Length: .703"
Shank Length: .625"
Shank Diameter: .375"
Head Thickness: .078"
Hole Size: 3/8"
Grip Range: .030-.227"
15 Per Package @ $10.46/pack
This may not be the exact size the RG's use, but from memory they should be similar to them and give you all an ideal of what's available outside the MOCO parts chain at a much cheaper price.
They also work great if you're trying to attach something to metal and you don't want to chip the paint or cause rust.
After reviewing their site a bit more, these plugs will probably be a better fit for the rider's peg holes. Keep in mind that the tapped thread is 3/8", but the through hole is just 5/16". So these with 3/8" shaft diameter will still push in tight and hold. I would not get the 5/16" diameter plugs because they will be a bit loose.
http://www.clipsandfasteners.com/Trim_Panel_Retainers_Ford_Chrysler_p/pas5643-50.htmHead Diameter 5/8"
Stem Diameter 3/8"
Stem Length 3/4"
Replaces Ford Explorer # N807721-S 1993-on
Trunk Lid Latch Chrysler #6504043 1996-on
50 Per Package @ $4.99/pack
This particular plug is for a Ford so maybe a Ford body shop will have them so you can get just the eight you need.