Commuting - Finding Park and Ride lots when there are none

I have been commuting 22 miles each way to work, but due to some injuries, I can't tolerate being on the bike that long. I am trying to go multi modal and drive half way and bike the rest. The problem being that I commute through suburban towns no where near public transportation or bigger cities so there are no park and ride lots or commuter/ride share lots, whatever you are used to calling them.

Anyone have any success in what city departments to call or strategies for making this sort of situation work? Specifically, I am looking for something in Millis MA, and I'd like to abide by rules and not lurk in a supermarket lot all day long because I plan to do this everyday since the distance will be much more manageable.

Thanks

Whats wrong with parking in the supermarket parking lot, if the store manager says its ok?

The problem is that some parking lots actually do have time limits and do tow. I don't want to run that risk. Also around here, the parking lots do not belong to the stores. The lots are part of big strip malls or shopping centers so one store manager does not technically have the ability to give permission when the parking lot belongs to some other private entity or town.

I do get your point that I could go to a single business with it's own private lot. That may be my only option, but I wanted to hear other strategies people have used.

Mall lots, office parks, county/city parks are some options. Anywhere there may be acres of parking which is rarely full. Go to the outskirts where no one wants to walk to the buildings.