If you see Triple maxim bullitins in loadout i always go mg(or pio like you want)-gren-mortar-mortar.
2x mortar just wrecks maxims, they cant Set up for more than 1 burst + forces them out of building very fast. Dont worry about field presence since he wont have that much too with maxim spam
How do people use Maxims? I always use them very aggressively. I don't camp with them until the mid/late game/until it's necessary.
You can use them offensively too when you're capping points. just don't set it up and it'll turn to face the first incoming squad. This works good on the flanks.
I just don't understand how two mortars will help you win in the very early game will help you against two-3 maxims after they suppress and then force a retreat on your single Gren.
Two maxims on 1 MG42 is going to destroy it 9 times out of ten (unless it's in a house somewhere)...but I'm talking about the first 3-7 minutes here.