I'd probably go with the lawn edging or the old fashioned DIY rubber flares (if that stuff still exists) too: screwed every few inches into the underside lip of the existing flares. Should be "permanent" enough to pass inspection but easy enough to remove for use and much cheaper than new rims, flares, etc... If you want, ultimately, to have full coverage flares then this might just be a fix to buy some time until you have the $$$/solution you want and you wouldn't have done any visible damage to the existing flares.
I don't see how something like that would be any different than having to de-tune my '73 to the point that it barely runs just to pass the emissions test, then retuning to drive home.