I run my BFG AT's at 'road' pressures, something like 32 - 38 all round, depends on whether I'm towing or not.
I run my Extreme tyres at about 20 - 25 all round.
The AT's track straight and true, the extremes don't, they're softer, higher walls and 'wobble' more ... I can't see how a set of road tyres on one end and a set of Muds on the other can work properly together, no matter what the pressure! The main reason Muds are recommended lower pressures is mostly 'cos they're for mostly off-road use and are a big compromise when on-road. Mixing and matching cannot, in any way, be any good for road safety.
I'd suggest get full sets of either and work from there, you're fighting to make different systems work together when they never will properly.