If the A-Arms are too strong will the mounting points to the body start breaking? Seems like you want the A-Arm to bend before damaging the bulkhead. What is the goldilocks A-Arm for this? Not too strong but not too weak?
Get the strongest ones you can find.
Nobody makes any strong enough to damage the bulkhead from a ski hit.
Encapsulated ball joints mean 100% of failures are arm replacements.
Alt impact arms are weak.
TREX so far have held up great on the sleds I’ve been around.
I just consider them a wear item and keep a full spare set on hand.
Fancy expensive ones seem to fail just as readily as cheap ones.