Chris congrats on your new 30WRS. I have a 2011WR. The only thing I can think of with the Boltiton system is, if your running Harley's you may have to stagger them so your not handle bar to handlle bar. It would depend on the models.
My WR did not come with D Rings. I went with ETrack and a Condor Chock. I ran three 8' length of ETrack (up each side and the middle) I staggered the condor chocks by about 6". I think you will like a locking wheel chock like the Condor. Condor makes a free standing with trailer mounting bracket and a trailer only model. I have the free standing with trailer mounting bracket. You can ride the bike into the chock and step off. The bike will stay up while you strap it down.
I usually only haul one HD Ultra but have hauled a freinds Ultra and they would hit if they were not staggerd.
I have done several mods on my WR. Good luck with yours.
I don't know anything about these two vendors I just picked them out so you could see what I was talking about.
E-Track Motorcycle Trailer Tie-Down
Condor Wheel Chock