This is where to post your more serious general questions and discuss caravan related topics not covered by other sub-forums.
Please use specifically named forums where possible in preference to Caravan Chat as this make it easier for members browsing a topic.
The big question is what is this "Modification" is it a taboo subject. Your brakes don't have brake pads they have brake shoes & brake squeel is associated with resonance of the shoes & back plate . One Automobile modification was to fit a weighted block with a rubber bond to the back plate to reduce resonance. Anyone noticed if you reverse against the brake overrun the noise goes for a while. The journey back home had no brake noise but we weren't in stop start traffic.
Durbanite, it's quicker to use google than the C&CC's website.
Just search "glos da", and up comes the Gloucestershire DA website with a link to their meets.
Or try "worcs da", to get a choice of East Worcestershire or Worcestershire & Hereford DAs.
As far as I can see the Truma filter seems to be the same as a the oil coalescing filter that can be found on compressed air lines. Regarding the Cleese single stage regulator the supposed down side is the oil contamination can supposedly pass through the regulator potentially contaminating the appliances. As suppose as ever you pay your money and take your choice