I use washing up liquid on a lot of surfaces and it is definitely worth having in the van.
I'm not sure, if you use washing up liquid, where it would fit into your clean up and or where Kevin suggested it should be used. I'm not picking at his suggestion.
But if you are going to wet vac up a mix of water, some oil and washing up liquid (dependant on how much of each part there is) you will also introduce air into the collection and the whole will be agitated.
This will foam the washing up liquid and the ball in your vacuum will rise and cut out the wet vacuum, thinking the drum is full before it is.
Non foaming whatever you use.
Chris's professor in his 'Anderson shelter' will have the answer but you are on the edge of what I find as quite an interesting part of the cleaning market, colloids, solubisers, emulsifiers etc and their use.
Mike will know because they use them all the time in their non foaming chems.