>>1712427A true composting toilet requires the user to periodically shovel out the partially decayed shit and dispose of it, (it doesn’t magically “compost” into thin air) whereas an outhouse only has to be eventually moved 10’-15’ away and a new hole dug after X years and in the case of vacation property, OP probably won’t have to move it for 20 years.
OP could even buy a small plastic tool shed at Menards or Homey Despot and easily convert it into an outhouse, mounting it on some non-rotting plastic composite lumber 2x4 skids.