Hello, I have done already what you want to do. Believe me, you do want to do it.
My Big eyes have had fellow shooters drooling at the precise optical accuracy of shooting long range matches and spotting hits on targets. These spotters also have spotted Mule deer lying in shade under a tree surrounded by brush at long distances when higher power optics could not see them.
A mount for these must be colimated properly in order to get the proper optical advantage a binocular has over a spotting scope. Jerry Phillips is your man at Metal Tech inc. 265 Airport road, New Castle, Delaware 19720. Obviously, this mounting is not strapping two spotting scopes in parallel on an aluminum plate. You gain virtually nothing by this method. You will absolutely need a Bogen or really heavy duty tripod to hold this setup stable.
I wish you well in this and hope you do not skimp as this route is the very best way. Long after you have forgotten the price you will benefit from the advantages. I share nothing with Mr. Phillips, but benefit from his excellent workmanship.
Gene S. in NM
