My hunch based on what you are saying is that it's the risk factor for the lender on the deal falling through, and the lender being stuck with land...the second issue is the unknown on the length of the loan if the national builder falls through.

Hey Pat,I have used both All Risk's program and Seattle Specialty for investors with 10-100+ properties. 

From the day we take title you then have 180 days to sell the properties you want to exchange into this new property.Reverse exchanges can be a great way to lock up your new asset first and mitigate some of the risk associated with trying to get someone to give you a contract contingent on several sales. 

If you are going by storm risk then there really is no true safe area. 

You could always run your numbers at 5-10% below that ceiling and also factor in the additional carrying costs.

Do I invest my money now and then liquidate when I have enough for my first down payment on a property or just save all cash and avoid the risk and illiquidity of certain investments?

The higher the LTV for the loan the more strict they get on every little detail to try and curb risk.

If you have more than one investor in the deal, don't you have to put them in second position where there is greater risk?

It's just going to be hard to get into your, and your dad's mind(s) with regards to understanding your risk tolerance levels, as well as your capabilities. 

Just paper yourself and understand foreclosure risk/cost.