D1 and 2 will get a bike in with the back seats down, I’ve had both, no experience of a D3 but it is bigger, so probably yes. You probably won’t be able to stretch out in the back, but not too cramped for sleeping, or in many of them the front seats go back almost horizontal. OK for occasional nights out, but not ideal for long trips unless you camp next to it, back is good for cooking / sheltering in.
Extremely versatile, very capable off road, but they are Land rovers with all that goes with it, see the previous threads on here. If you get one, especially one of the older ones, you’ll either hate it or it’ll end up like the old smelly incontinent family dog that you can’t bear to take to the vet.