“Mechanical” tempomat

Moin I am recently owner of a mobile home, unfortunately without cruise control and electronic motor control. With the latter it seems to be no problem today and install a cruise control, with an old VEP, however, all manufacturers seem to have stopped producing cruise control. Has someone here still sold a cruise control dealer with pneumatic VEP, or even one that you can have? Or another good, working idea? All other cars I have to keep my foot in a position for hours on holiday… Moin Björn