I've made cases out of 4" PVC for my fly rods.
Virtually unbreakable....mine made it all the way to Diego Garcia with nary a scratch!!!
Would work for bows also.
End cap on one end and screw top on the other.
You could even wrap metal strapping around the case, nail it to 2x4s, and put those in the stake holes and lag bolt it in.
When you want your bow...unscrew the cap.
It would never blow out and it would look like just another tool case, seen plenty of long cases on trucks for long levels, tripods...etc.