and: With the amount of own work, one year is never enough. You also have to add the time for the building permit application, approval, infrastructure, etc. And even a 45K wooden kit house doesn’t build itself. Without a crane or at least a few strong helpers for several weeks, nothing works there either. Someone still has to sign the plan, either an architect or an architect from a general contractor (building submission authorization).
P.S. I struggled with the idea of building a TinyHouse (not "Rolling") for some time (also stayed in one). Looked at various kits, researched, etc. Without land, it was always at least 100K if permanently habitable (primary residence!) according to the energy saving ordinance.
First make precise and above all feasible plans, have them checked by experts (costs money!). If you get the green light here (and only then) sell the condominium as suggested above but rent it back yourself (the market is totally crazy at the moment. Maybe you get more than you expected?)
With a lot of own work in construction, much is possible, but please do not overestimate yourself. For example, I currently work 1 to 2 times a week + every Friday afternoon + Saturday full-time on the construction site and it really takes a toll on my strength (I’m 53 ...). I couldn’t handle full-time all week. I’m also never alone on the construction site. Even though I know why I’m doing it, I have to motivate myself and that’s much easier with two. (Very) many things simply don’t work alone.