As long as you don’t throw in anything that’s restricting to their current lifestyle they will sign.

Also, am I able to fund the renovation with expectation of a repayment since the down payment gift restricts that?

Most housing authorities have a form for this, and some restrict the time frames.  

Being tied into owning a home can restrict where you can work and, therefore, your earning potential.Homeownership also ties up your cashflow, and the more expensive your property, the more that’s true.The biggest mistake I see young couples make is not having a personal balance sheet that has a net positive cashflow.

Some condo associations restrict the amount of time a condo can be rented, who it can be rented too, and what kind of modifications you can make - they may outright ban AirBnB.Additionally, consider how you are purchasing the condo, traditional financing can get a bit strict around Condos.

In South African usage, the term bridging finance is more common, but is used in a more restricted sense than is common elsewhere.

If the owner and/or tenant restricts access that could make things difficult for you. 

I am also pursuing a flip using a 203k loan, but that is certainly not without its own restrictions and headaches.

One must consider the amount of demand +, the amount of supply entering the market +, the fact that rent control severely restricts inventory turnover of existing stock +,  drives away developers who do not want to be in California due to rent control.

With delayed financing, you have the restriction of pulling out a max of the purchase price plus closing costs prior to 6 months.