Tandem towing behind class A

Sounds like a bad idea to me for several reasons. Lots of weight for 1.

Even where double towing is allowed the first trailer behind the tow vehicle has to be a 5er in NM and most other states that allow it or you have to have one of those "hitch hogs" in the mix like the semi tractors use to tow tandem.

Welcome to the forums. It would help if you put your rig in your signature. The states that allow double towing often require a fifth wheel hitch on the front tow...not something you will find behind a MH very often. A max of 65' is the norm in the East so you will likely be over that length. At 800+ lbs each putting them on a lift behind a MH would only be possible with a tag axle coach.
Good luck as you're going to need it but 96" is only 8' so you could put them on a trailer sideways.

Street Glides are 96" long, so I don't think they will fit a trailer sideways, the way I see it you need a trailer long enough that will fit both the car and the bikes, I know this isn't your preference, but it will be your best option, I know several people that have this set up.
Good Luck with whatever you choose.

Towing two trailers not allowed in some states, particularly along east coast. And length can be a problem as 65' is a common max overall legal length.

If the car is small enough and the trailer long enough you might get the two bikes crosswise and the car behind on one trailer.

A flat bed trailer would be the only real option I can see. Why not an enclosed trailer? Safer for your bikes. Carefully consider consaquences of a rig that long and it will limit camping locations as well as parking,.