i wfp everything, ground floors, 1st, 2nd, 3rd plus floors, frames, doors, conservs, conservs roofs...caravans, cars, vans
wfp is the best thing i have ever done and wouldnt go back
i reccomend starting off with a backpack, although i have never used one, it does seem to be the cheapest option, then you could strap it to a trolley eventually if you wanted to.
i currently have 100m of hose out of the back of mine, and i will eventually get a backpack and strap it to a trolley so i have all options.
to be fair actually, they all cost pretty much the same, but then you gotta think how much your van will holg, 1kg = 1litre, or there abouts. i didnt get on with a trolley, and i love the van setup, much easier