DIY 4x4 kits or guides?

So I am looking into purchasing a van and converted into a camper, then become a total hippie and travel the world making youtube videos and short films to finance my adventures. pretty solid plan right. All I need to do is pick the van. Im between a promaster and the transit. The promaster has a longer extended version (160.2") which gives more room in the cargo versus the transit extended. interior space is extremely important and so even a small amount of room can be critical. This makes me want to go for the promaster. However, since I want to bum around the world, that will probably take me to some pretty inaccessible places, which makes me want to prepare and have a 4x4 van.

The real issue is that I dont have the money to get a 4x4 transit/promaster. but since I plan to roam around the US for the first year or so, and I expect to be able to drive to many interesting places without the need of 4x4, it upgrade can wait. once I leave the US though, I expect to need the 4x4. So I am just wondering which one in your opinion is better for converion.

Also if the transit is better for this, is there any DIY guides out there, kits etc. There is a mechanic that I know of who works for very reasonable pay, great guy. I myself are not afraid to work and use tools, I have experience in the aero industy (but I lack experience in the auto industry). I read that quigley uses mostly standard ford parts so only some require special modification. Basically I want to know if its reasonable to want to upgrade and do it myself as I dont see me paying 12k+ for it.