heat may be a long term issue. so have you thought about a heat resistant section of flexi hose from the guard to the motor/intake?
if you are as bad as me when wheeling, you will know that the motor moves from side to side a lot. plus, not to mention when you break the engine mounts like i do all the time. i just don't think that the pvc pipe and the little rubber joiners have enough flex/give in them to cope with the engine's movement when driven hard.
even if you have to hood up, and you rev the motor, you can see that it already moves a bit with even no load on it.
if you are worried about breaking engine mounts, or if you think the motor moves too much, you can either make new engine mounts with sammy leaf bushes, or just get some HD chain and chain the block to the chassis so it doesnt lift.
this latter may not be as good, but you find you get a more direct feel when accelerating, and wheeling, and especially when you put a lot of load on the motor.
so maybe look into that. but overall, looking very good.