We have a T4 we don't pack up to move about. Although say we have breakfast, plates get washed & put back, everything has a home, so we tidy up as we go along. As you don't want to get back to everything everywhere.
The awning we have means that you can't just drive off. So that's good say for festivals, when you know you won't be moving.
The T5's have a roof space thing, so that's another double bed. You can check eBay, autotrader, sites for campervans.
It was a biggish job taking out the old interior and doing it up. There's electricity points, USB points, a stove, a sink, the toilet is under the stove, we have a tent for that if there's say no onsite toilets.
There's a festival at Santa Pod at the end of July, that's a great way to see what others have done, plus on the market bit there's stalls selling bits you can use for doing up your van.
You can get a van and strip it, then it's up to you.