I'm sure similar business ideas have been pondered my most expats here. All about finding the right bit of land.
Building to rent or sell. Big or small houses/villas. I would like to build estates like BTN only better quality and slightly more upmaket. They have a good model, they put the roads and services in place, divide into plots and sell the plots with the contract to build before building commences. Progress on the building depends on the ammount paid.
Their plot sizes start at just under 1 are upwards and tend to sell very fast, even at a premium price. The finished products are in reach of locals to buy as well as tourists.
So land, planning permission, sevices [water, electric] and a basic road and very little more investment is needed.
Tricky though having partnerships, as you can well appreciate.