The solutions are fairly trivial.
At work (industrial electronics), we don't do any aviation stuff but we make a little box (email me if interested) which functionally is very close to doing exactly this i.e. turn on a relay from an SMS message, for X seconds. It costs about £300, including the GSM modem.
That's what I would do if I had a strip and wanted PCL. IME, SMS is more or less guaranteed to work below say 2000ft.
The
FUD surrounding PCL goes back many years, to some old boy in the CAA who has long retired. I would bet you anything the CAA would never enforce it today.