I’d got a Whyte G-150 with stock WTB TCS tyres and rims. I went tubeless about 6 weeks ago and the front has been trouble free. However the back always deflates over night after a ride. I’ve had a look at the sidewalls of the rear tyre a WTB Wolverine and they are work in places where I can see the carcass.

I’m riding pretty rocky tecky trails which the back wheel is always skiting around on hense the wear?

So far I just pump the tyre up and it seals again, with a plan to get a Maxxis High Roller II with EXO protection to solve it?

Am I on the right lines?

Yep. Assuming it’s always done that it may just have a tiny leak in the carcass of the tyre, try really giving the wheel a shake to distribute it around the sidewalls.