May not be the entire answer to your problem but.....
Look for some glow in the dark tape called SAFETY TAPE. It is a light green cream color and with a few seconds of exposure to a light or LCD white light flashlight, will glow in the dark for 7 hours or so. It is just a glow and not a light source so won't bother your night vision. I use on scopes, tripods, etc. to help locate tripping hazards in the dark. I learned about it when I was working as a Safety Engineer before retiring. They use it in building exit hall ways placed low on walls. If lights go off in an emergency you can get low to avoid the smoke and breath as you leave the building in a fire. I introduced it to the astronomy club I belonged to in San Francisco and later when I retired in Michigan 14 years ago...to the club here. Virtually everyone in the three clubs I belong to here uses it. We buy it in 100' x 2 " rolls. It is so popular here we already went through one roll and 1/2 way through our second.
Look for it if you think it might solve your problem....if you want a small sample I could mail you a piece if you send me your address....
biker123 at att dot net
I have a 900 and 1100 mount mounted on flat pier adapters on a permanent pier and also a heavy duty tripod for my own use. I don't think there is any existing riser for that but you could simply build a spacer using hardwood stacked up and cut round to match the flat plate ring. The wood would actually be beneficial in vibration damping. Alternatively you could have a machine shop built a box riser although that would obviously involve a lot more expensive material and machining. I have my own welder, metal lathe and milling machine so that would be easy in my case.
Also....how is that double pier working? I have used the single pier model on a 14" Celestron HD SCT mounted on a Celestron CGE-Pro mount in an observtory I designed and manage for boy and girl scouts here. For visual it is just barely usable but horrible vibrations that last a long time so useless for photography. I finally had to build reinforcements but that eliminates some of the ability to raise and lower it that we wanted. The sad part is the company that makes it guaranteed it would be fine and after installation said "Guess we were wrong." And told us we couldn't return and get credit for the larger capacity model. Needless to say we weren't happy.