Re: well that was soul destroying.
I don't know if it's anything like the 164 V6 oil filter but I have a big Jubilee clip with a 6mm bolt about 75mm long tacked to it to form a "handle". I can slip the Jubilee clip over the filter and then tighten it with a 7mm socket on a long extension bar (or a long screwdriver), leaving the bolt sticking out at just the right angle to let me grab it with a finger and pull downwards. I usually have to do this twice, repositioning the jubilee clip each time, before the filter is loose enough to go the rest of the way by hand. It has never failed yet!
As far as the washer is concerned, I use "Dowty" washers (about 50p from local hydraulics shop - just take the sump plug or the old washer as a pattern. They have a plastic insert moulded into them for hydraulic sealing applications and I find they never leak.