Guess I can turn this into my Bane Russ build experience to see if it actually works. I will do the math and designing before I start cutting.
I took out some Leman russ pieces from my bits bathtub and a Baneblade/Stormlord side and scanned them in my flatbed to get exact measurements.
This is how I decided to do the photoshop cutting.
From doing some cutting in photoshop I came to this, from what I can tell this is the most efficient way to do it. You can do it the other way around with having the front piece have the side panel but you end up with a bit harder to cut back piece.
The bits line up almost perfectly for cutting and since the 1 part that needs cutting is the exact same as the left bit you can probably cut it without leaving too big a mark.
This is what you end up with.
This is what the pieces look like side by side, as you can see they are almost identical in size. Once you add tracks the Baneruss will be longer but as that makes it a bit bigger (easier to hit) I dont think your opponent would mind half an inch or so.
Next step will be to compare the main hull and threads, there will have to be some mayor cutting done to these parts to shrink it down to Russ width, if this can be done I believe it's possible to make a Bane Russ that's actually comparable in size to the normal Russ.