For those who take loans using Bitcoin as collateral

All my wealth, which isn't much, is in Bitcoin. I want to build a modest house. I live in Latin America, where interest rates are high, and to get a loan from the bank, you need to declare an unrealistically high income, which I can't do. However, I think I can build my house while Bitcoin appreciates in value until December.

For those who have experience with this kind of operation, any advice besides keeping the LTV at a healthy percentage? And how can I benefit during a downtrend when Bitcoin starts to drop, to try to increase my position? My goal is to never sell my Bitcoin, which is why I want to pursue this strategy.