WRT a poncho, I recommend any sturdy plastic poncho, nothing that looks military. At least until you are home.
Home Depot , Lowes, Basspro, all sell super cheap ponchos for $4. Those are your spares.
Buy a $14-$20 plastic poncho in a bag for you. Blue.
The military ponchos have a couple of nice options you don’t see in civilian ones: the option of snapping a few together and connecting the poncho liner for sleeping come to mind (besides the camouflage itself, which may or not serve you well depending on where you live/work - then again, you can always just get the OD colored one).