Most people have a regular shytting schedule. It's not common to spontaneously need to shyt. Combine that with the fact that she will probably eat before the sun goes down / night (more restraints open she can sit down or eat alone in a park - she'll probably take a shyt when she wakes up and becomes active, then after breakfast probably shyt again mid day.
People do it, I don't know how they get good sleep. When I park my car I glance at my surroundings get out then go in, come out load up and leave. I never see people sleeping but if you watch people long enough there are people that walk by and look into vehicles. Most family vans have dark windows so someone would really have to peer into it which isn't common, if a car pulls in and no one gets out and the engine shuts off something ain't right. Keep in mind you have to be discrete about it because you're going to have certain spots, not just one that you routinely sleep / park and if casual people who are attentive (like me) can pick up -that Grey van is always if not always here...ive seen it pull up but no one ever gets out. Or better yet a woman got out and grabbed something out the back then went back in...
Now you're a target.
It seems kind of weird but people sit in their cars and smoke ( cigs or weed) especially if they work there, if not just a chance to get out of the house away from husband/wife/kids/mom/dad/etc , people sit in cars and talk on the phone, drink (alcohol or coffee) during these times those people are observant, with nothing but time to count the cars and do their task. It sounds crazy but there was a woman who would bring her kids to work and leave them in the van while she worked 530am to 1pm. I'd go out at 8am to chill in my car and drink coffee on a nice morning (sometimes open the roof and let the morning air, fresh cut grass and air do what it do) just enjoy the cup - - anyway all of a sudden 2 cars over this family van starts rocking and I hear children's voices...i had plenty of time to put the shyt together 'daycare prices too high, single parent...you gotta do what you gotta do' plus one time I saw her come out and check on them.
I would definitely cop a handgun and a ccw. Go to the range and fire at least 500 rounds then do whatever you want with the confidence that you have a better chance of protecting yourself.