I love the joy stick.
I would consider mounting the electronics on the other side or the under side of the marker to reduce profile sticking out from a bunker. (assuming you're right handed)
As far as your other trigger
you could rig up one of those grenade launchers rap 4 makes. that would be awesome.
Or a silly string can to blind your adversaries. (which may just be the funniest thing on the whole dang field)
My personal favorite would be to rig up an electronic squirt gun full of paint as a "Flame thrower".
like this thing http://www.amazon.com/Saturator-AK-4.../dp/B003A01ZC4