I sometimes do water enema before going on road trips so I don't have to do #2 in public.
I do have a collapsible toilet where you do it in a bag, but that is just for emergencies and I rather find a public toilet.
I mostly use a bag, but I sometimes use the a nozzle connected to the shower.
Have to be very careful with the latter and is only for experienced users.
Shouldn't hurt at all, so stop when it does, let body adjust and try going again, if it still hurt then you are full.