90 octane on 8-10 psi

So I live in Alaska and the best fuel we have is 90. I'm ready for a supercharger on the 7.3 godzilla this summer. My question is, is it best to run a 90 octane tune or run water meth, or octane booster? We do have AV gas which is 100 octane I belive. But I'd rather stay away from av gas for my daily.
How much psi would you push on 90 pump gas and when would you want to run water meth or booster and what booster?

It's a daily pickup and hauls up to 15k often.

I'm not sure of the godzilla but I've got a few customers I've done Turbo LS's in trucks that tow often and got them on 87 octane and under 10psi. Timing is absolutely critical. I'd suggest Water/Meth just to help keep it cool and help with detonation in boost.