Great Bikes!
I crossed Russia on a 62 HD panhead chopper in 09, and this summer, went to Magadan on a sportster.
The road across Russia is in much better shape now, in fact the far eastern part is now all paved, and to euro standards.
I hit a total of maybe 50km of bad road this year, but that should be fixed this winter. You will hit the occasional bad spot/potholes which will be harder to avoid on a trike, so be careful.
As for your question, I dont know of anyone thats done it on bikes like yours, so yes, it should be a first!
The Russian bikers will love it, plan to be detained alot, and to meet ALOT of people!
Of course you will be stopped by the police, but not for anything bad, they will just want to see the trikes & get their pictures taken on them!
(just make sure you dont cross the solid white center lines, or speed thru the towns)
If you are on the main road, the farthest stretch without fuel is about 250km.
I'll probably be back in RU next year on my old shovelhead, so maybe see you there

Feel free to contact me if you have any questions, I've crossed Russia 4 times.
Doug