I rarely have the back seat in so normally they are in the front seat. I would suggest that if you want to put one anywhere close to target you get out and practice a bit before showing up to a gathering and trying to learn on the spot. Know the rules they will have as dropping from 50' is much different than dropping from 200' AGL.
I got pretty good at dropping 50 pound grain sacks to a friend on a remote horse hunt, but that's a different story all together. Ended up with 8 sacks of grain within 20' of each other and most were stacked.