We get this question asked to us a lot. We generally don't recommend this as like building a home in stages makes things complicated and a van is no different however we get that this question mostly arises due to budgets and/or time involved. If you are going to do this we have some recommendations in regards to practical things to do to get your van to work. We are going to focus on the practical most impactful things to do and most importantly in the right order. Just like building a home...you need to do things in the right order. (This isn't upgrading your wheels and tires)
Stage 1 (get your van useful; generally 6-12k)
If you want to get up in running quickly, as we recommend start with a Sprinter Crew or Passenger van, it has 90% of the walls, floor, and a head liner, seats, windows, and front table system. Most of this does not require you to take the van apart and can be done in stages.
You can easily transform this into a campervan quickly by:
Installing a bed, vented windows, and if a crew van paneling the rear quarter of the van so you don't dent the side of your van from the inside and it will quiet it down a lot. You have to get air in your van (its hot) and a fan is useless unless you have windows with screens. So start with the windows, and those vented windows dictate where your fan will eventually go. You need a bed so you can store gear underneath and that's what makes a campervan and a bed makes a campervan. Lastly, panel those exposed walls, a dent in your van is very expensive to fix or in some cases cannot be fixed easily or cheaply. If you are going to install pill windows or vented windows do that as well before paneling is ideal.
Roof Rack...yeh we get it you look cool, however you should put your fan and solar gland prior to putting a rack on, otherwise it all has to come down. This is ok...but your going to have to pay twice. You also need roof rack rails on a Sprinter to install a rack. You might realize after installing solar panels and a fan...you have no roof rack left and just dropped 4k...
AMA Vented screened windows are easy replacements on to factory oem windows.
Adventure Wagon bed, rear quarter panels with window insert. Upper storage, fan, lights must come in stage 2. (van must be taken apart)
Swivel seats and Lagun adpater mount with Lagun arm and table.