Would love to use a few of the ideas you have on my own bike- same filters and removing the rear mudgaurd. .
So why don't you?
Don't get hung up on 'legal', most cops have no idea about construction and use, or even the finer points of law and if it's passed MOT that's enough, if it doesn't you take the MOT testers advisory, put it right and go for a re-test.
Two examples:
My bro-in-law was stopped on his '75 Triumph trike in Southport, copper says "You know why I've stopped you don't you?" Dave replies "Actually no, I know I don't have indicators, but it was built and registered before 1986 so I don't need them, it DOES have a handbrake, it has an MOT and is insured, it's also tax exempt, so why
have you stopped me?" "Because you're not wearing a crash helmet!" There is then a 10 minute war of words culminating in the policeman radioing the station to be told "Actually, the rider is correct, he doesn't need a crash helmet on a trike"
My neighbour got stopped for overtaking on chevrons, again the copper thought he had my neighbour bang to rights, until it was pointed out that it is legal to overtake on chevrons, providing there is a broken white line on your side of them.
So, forget the 'legal' hang-ups and go for it!