The savy buyer will appreciate the quality upgrades & know the difference between things like a modified sine wave inverter & a pure sine wave inverter. To retrofit many things would not be worth the time.
Like the OP, I am in this one for the long haul. It is the first. It is planned to be the last. After 9 years we have not seen another that we might like better. We have been to shows just for fun.
When we sell, no plans to soon, it will truly be 'turn key', right down to tools & spares carried like landing leg bevel gears & a still in the box waterpump plus all of the tools. All the new owner will need to do is stock the fridge & put in their own linens.