I'm I think 3 years in to van ownership - VW Caravelle with most of the seats removed.
The interior fit out is constantly evolving as I get different ideas.
My thoughts.
Boards on the roof. They are always wet, covered in sand. The quantity of sand that gets in the van without them is pretty amazing. I'm on SUPs, so most too big anyway. If security is an issue put them inside, otherwise tied on the top.
I have an Engel fridge / freezer running constantly. Have had for 20 years in work Landcruisers as a surveyor working on remote sites, have always had a dual battery system with the second battery isolated so the main one can always start the car. The fridge murders the second battery though, running it dead flat if you are parked up for a few days. Cycling it dead flat to fully charged kills the cells. On this van about 2 years ago I got a solar panel fitted, and an AGM battery (don't know what that means) and no issues since. The solar works even part obscured by boards.
I originally set up with a 2 seat back seat, full length bed behind it, storage for a bike next to it. As time went on, and rounding down a bit, I never rode the bike and never slept in the van. Big area of dead space at behind the seat / at the front of the bed.
Have recently fitted a 3 seat bench a row back, more room in the main cab, less dead space, if I want to take the bike it will fit in front of the bed.
"Kitchen" at the back. If you want to cook, stand behind the van. Cooking inside stinks it up badly. I mainly do coffee and toasted sandwiches.
Forgot to mention, 1000 watt 240 volt inverter hooked up to the auxiliary battery and the solar. Will power a kettle, sandwich maker, battery chargers, music. Makes you pretty much independent of powered sites if doing the caravan thing.
Hanging space. For towels, wetsuits, etc. I have drying racks just below the ceiling, hang everything there, never take it out of the van.
Can lead to the Van smelling "Really quite bad Dad" as my eldest daughter put it in mid winter in Melbourne.
Some photos, not stretching back to start of Van ownership, but covering most things.
The downside of VW ownership - broken timing belt 99,900 km (out of warranty). Pistons met the valves not in the order VW intended. New engine, expensive, close to scrap the Van cost.

Happier times.
Back kitchen, fridge, single burner gas stove, hanging wetsuits, bike (a bit hidden), board in the bag is a 6'6" skateboard.
Self built boxes and drawers, I have a lid that goes on the left when the bike isn't there.
Build is just pine planks, self drilling screws, black paint, outdoor carpet.
All available from a leading hardware chain I hate.

Kettle on, coffee ready

Stove basic butane cylinder single burner thing

Baked beans and toasty soldiers at the back of the van

Or sardines on toast....

Rhino Racks side awning, wall, and tag along tent.
Pretty cheap and good quality.

Swivelling bases on front seats to give lounge area.
Steering wheel gets in the way.
Suction cup black out blinds, lots of stuff from justkampers
There's probably a .com.au after that

Bed in place, back kitchen, awning

240 volt power for external music

First version of the current evolution.
Two seater out, three seater in, one row back.

Modified back kitchen.
Had to shorten everything a bit.
Forgot to mention - inverter powers the microwave too - lowest power I could find, probably takes four times as long as your home one, but works.

Dog likes the more room at the front

Back kitchen finished a bit better - mainly black paint

Current project - aspirations of carpentry skills, going to clear finish under seat cupboards.
Above seat wall old skateboard table with stickers applied.

And the final word from the eldest creative daughter.
Father's Day present.