We have made double ring belts in the past, they work but bridle leather is quite dense for them when its new but fine when its broken in a bit. Drop me a pm and we can sort out a plan Im sure :-)
Sadly there arent a lot of buckle available in 1 3/4" - the foundry we use don't make a lot of the patterns in that size which is a shame. The West End is a really nice buckle in that width though if you do want one, not as interesting as the two you mention maybe but the proportions and construction are really nice. We can also get a 1 3/4" Brass West End Roller for a slightly more casual look I think - still not what you were after though I appreciate!