I think you are overcomplicating things. You make an S.A company (add the electricity provider as a partner) while retaining the rights to the equipment yourself. I don t exactly know how to explain it, I don t know the juridical terms in English. I think a notarized agreement should work, or it can be stipulated when you choose the type of company (SA. SRL etc)
It can be quite straightforward
I'm not sure what he's asking either by trust. The issue might be that as a non-national even a notarized contract could be broken or he might get robbed. I too would have some concerns going into a foreign country where corruption is fairly rampant.