I suspect that people with expertise in Maltese Air Law are pretty scarce.
I have an aeroplane with an EASA CofA that I rent to a flying school in the UK. I insure and maintain it, the school puts fuel and oil into it and provides parking and cleaning. They pay me an agreed amount per hour, we have a written agreement covering a lot of smaller detail like who ferries it to maintenance, responsibility for the insurance excess, what to do if it gets stranded away from home base, how we adjust the payments if I use the aeroplane myself, the minimum amount of fuel we leave in if passing it to each other, notice period of cancellation...
I have a friend who has a similar aeroplane which he rents out to hour builders. He insures, maintains and manages parking of it. His renters pay per hour dry plus fuel and landing fees.
G