Sounds like a good idea Ken,
By cross bracing, do you mean laying the three scopes side by side (three in a row)? That being the case, you might want to shift the SCT in the middle and have the two refractors on either side
Just make sure you get a long dovetail bar with the ST 80 and that would give you more mounting options/positions.
Love to see the final set up (and result pics of the sky).
Cheers, Bo