Now the deposit covers up front costs , some materials , overhead and PROFIT .

Nowadays many vacation homes are priced as STR businesses with profits baked into the price (with future guests expecting instagram furnishings).  

Define roles, financial contributions, profit-sharing, and responsibilities in a detailed agreement.

However, we also recognize the time value of money, so while it might pencil out to turn a profit, but we get an immediate payback versus a six to nine month holding time, it might make more sense to sell them both as bare land.  

Quote from @Isadore Nelson: 180k + 40k, sold for a 'profit' at 218k? 

ST rentals are much more profitable and command cash flows are often higher than in the US if you buy the right property in the right market.As an international investor, I find Ladislas Maurice interesting but there are different types of international investors and most international investors I know wouldn't go through the hassle of what he does for the kind of returns that he gets.

Do you need an S-Corp depends on your overall tax situation and profit you are expecting form this flip.This post does not create a CPA-Client relationship.

Educate the land owner on the potential profit run the numbers and go over the basic proxy and blue prints.Make sure you have a seasoned and qualified Builder/GC because they can be a deal killer with wasted time and inflated material and extended completion dates.

If i lived in San Jose, the first RE investment that i would consider is a local property with an ADU that had distribution on the lot that would allow a profitable lot split.   

It is very much case-by-case and requires understanding of the current tax regime for personal itemized deductions, as well as gambling on the proposed changes to this regime by the next administration.