3D print integrity relies a lot on the method of 3D printing, the material used, and the design of the 3D printed part. For example, I have printed out some hotshoe mounts for DSLRs that have really withstood some serious use without showing signs of failing with PETG on FDM.
General use PLA on FDM printers wouldn't be my first choice for a v-hook, and I certainly would not mount it with glue. Depending on what materials your printer can handle, ABS or PETG would be a good start.
To mount the v hook using screws, I'd recommend something like
this design that actually gives you a way to screw the vhook mount to your spirit halloween proton pack. That design is pretty solid, with my only real complaint being that I wish the "Spirit_Female" part were a little bit thicker and the male part accommodated that.
I would also like to point out that that design is meant for the thrower that comes with the Spirit Halloween pack, and not a full size thrower. If you are putting a full size thrower on there, please, protect your investment and, like Kingpin said, just get a metal v hook of some sort.