When do you stop making mods?

The problem with mods is that depending on how they're executed some are difficult to totally impractical to remove later when you sell the unit. I'm as guilty as anyone, having modded the life out of every camper we've ever owned, some ultimately not so good, others that proved in time to be invaluable, BUT if there's ever another "next" camper for us I'll keep the mods to a minimum and those that I do go ahead with will when possible be designed so as to be easily removable later. Case in point - I've always installed a powered potable water transfer system on any trailer we've owned, next time it'll be portable with the pump mounted in a case of some sort, totally separate from the trailer itself. Same with any inverter I might want to use - portable. At least my hard wire EMS I was smart enough to install so it can be instantly removed at any time. :B