Maybe when you are actually travelling you could use a haybox. Put together a stew in the morning, cook for half an hour then pop it in the haybox in a secure place in the van, then your dinner's ready when you arrive, slow cooked and delicious.
I used a pressure cooker a lot when my children were young and I was working full time, so we could have a proper meal every day. Since they left home I have never used it again, as the time factor is no longer a problem. I found the pressure cooker seemed to blast the ingredients to smithereens and the meals tended to taste like school dinners. I much prefer a slow cooked meal. I don't use a slow cooker as I've never got on with them, so just use the oven on very low.
I use the haybox when we are visiting one of our sons who lives a bit over an hour away. I cook a roast til nearly done, pop it in a haybox and let it become really tender over the journey. They provide the veg, so an easy meal for us all.
I have cooked stew in a haybox too, although I heated it up on the stove halfway through then put it back in the box to finish cooking. I don't know if that was necessary. You could make a slightly posh one with really good insulation, as the hay/straw does get a bit messy.