Wow, never heard of fields banning co2. That sucks.
As for what to do with the KP. I dunno, I don't think I could own as many KP's as you do (it sounds like you have quite a few) and not send at least one
of them off to Palmer's for a Hurricane conversion.
But I guess if you want to be a purist about it, you could always just pick up a stock and trigger group and send them in for a scratch-built Hurc.
Personally, I wouldn't have any problems with "defacing" a classic for a Hurc conversion. But that's just me.