[Calgon]

https://sampwiki.blast.hk/wiki/OnEnterExitModShop
https://sampwiki.blast.hk/wiki/OnVehicleMod

You can use the callback [OnEnterExitModShop] to teleport a player back out of the modshop, and prevent use the OnVehicleMod callback to reverse vehicles being modified if the interior the vehicle is in isn't 0.