Hi and welcome to the forum!
I've been getting rid of my stuff over the last several years. It's been challenging. One tactic that I've just started using is to mark out an area in my house that is the size of a van (6'x10'), and then only living with what I can comfortably store in that space. It's been a bit tricky because I'm married and hubby isn't a minimalist, but I'm making progress.
That means I'm only keeping items that have more than one use, and also keeping only one of each thing instead of storing spares. I've got rid of my knickknacks, pared down my clothing lots, scanned photos to keep electronically, etc. The hardest for me right now is giving away my crafting supplies and selling my camping gear. I've sold collectibles on ebay, everything else on craigslist, and what doesn't sell I donate to a local thrift store. Because I'm taking it slow, it's a bit like pealing off a Band-Aid a little bit at a time. While I'm taking years, others have ripped it off in a matter of months.
Anyway, I just wanted to give you the idea of practicing living in a small space within your current house. It might help you figure out if you have things to sell or give away that will make the transition into a vandwelling lifestyle more doable.
When I am on the road, I live out of a Prius. In preparing to do that, I find that thinking like a backpacker makes it easier to figure out what to bring in such a small space.
The best to you as you figure out the best path to your happiness.
Suanne