I actually posted about this last month, Bristol isn't the only place, Glastonbury has the same issues and is clearing them out.
I am on a couple of vanlife forums and these issues are causing real arguments on them, pretty much the same as here to be honest over CMers. Some are just entitled idiots and think it's their right others realise its going to destroy vanlife! Since I have had vans which is nearly 20 years I have noticed big changes, I no longer tell others about my weekend parkups otherwise they get flooded by non movers! Sound familiar? Anyway we are careful and leave no mark where we have been, we have also done litter picking when we arrived in a particularly nice spot that was blighted by either vans or cars rubbish.
Of course the reality is a lot of these vanlifers do have money and houses and do this for extended holidays, others are working and can't afford anything else but a van and then the others it's a wreck or homeless. Maybe we should treat these as illegal migrants home and feed them from the public purse?