So more of a WWYD rather than AIBU.
We live on the edge of a new build housing estate. We’ve lived here for 7 years now and have a parking space directly outside the front door. As with new builds we’ve been crammed in like sardines and the opposite side of the road always has some cars parked up on the curb. It’s always been a bit tricky manoeuvring in and out, but we’ve gritted our teeth and done a 300 point turn to get out.
In front of us is a terraced row that predates our house. Our front over looks the back of their properties. Now the house opposite has put a gate out to the back that goes onto the pavement.
Last July, mid lockdown 1, they acquired a Winnebago. Not a small thing but a massive American style house on wheels. We wrongly thought perhaps they were having friends over for a week and didn’t say anything. 6 months plus on it’s still there. Parked up on the curb (in fact they regularly put a clamp on one of the wheels). So to paint the scene you can’t actually now use that bit of pavement and it juts onto the road massively and makes reversing out a real pain. It’s also really not a great selling point for our house which we do hope to sell soon.
Every few months they’ve moved it, we think around the block to make sure the battery still works. When they do that they place these massive orange barriers across the pavement as if to reserve the space for their return. I have been known to move these 
and other people with smaller vehicles have parked there. Once they go it’s back there in a flash. It literally goes nowhere. It’s also been there so long grass and moss are growing on a fairly new pavement ruining it.
To add to this outside the front of their property is a large square that has loads of free road space, it’s just not quite as easily accessible.
WWYD? I know my neighbours are getting equally frustrated with it but we clearly have no claim on pavement. Any tips?