Hi Mac and
to the forum.
The MP5 should be fine for continuous stop/start use, and you can also reduce the acceleration setting to reduce the initial power being supplied on initial take off for improved range.
Unlike the 250W geared motors, the MP5's controller has a built in temperature safety cutoff to protect the internal controller, and the stators on the Magic Pies are very large, so the generated heat is dissipated over a much larger area, and I have never seen
(or heard of) Magic Pie stator windings that have been damaged from excessive heat.
But you may need to reduce the controller's maximum speed and current settings to comply with local legislation if they are to be used for highway use
(or possibly reduce just the current setting to prevent the battery from being overloaded if you are using lower power batteries for offroad use).
Alan