If it was very efficient, you wouldn't have to worry about dragging a generator around, fueling, servicing, starting, listening to....
We can go for more than a week without any recharge, including 12vDC fridge use.
Indefinitely with a bit of sun.
All without turning the key of the truck, or sucking off LP.
Its a system that pays you back, in full, many time over, that is 100% silent.
That's why bother.
Obviously if your camper cannot support the weight of you on top, stay off. All the more reason for a hatch for access.
But not all campers are created equal. And even run of the mill campers now days are designed to be walk-able.
As for holes, none to worry about. The entire roof is coated in Gacoroof.
100% silicone roof coat, that will never leak, and will most certainly outlast us all