The 50% rule, gives you a wild guess based on assumptions that may or may not be accurate for your property, that the formula assumes generates a WAG for all properties.Forget the 50% rule, or any other rule, where the answer is based on a percentage. 

All of the assumptions you have used for running numbers actually are quiet reasonable.

This helps mitigate biases and assumptions, and it helps others make good decisions and take risk based on the information that they receive from others.

VacantAll NNN lease with expenses reimbursement from the tenants. seems like a good location as it is just off of freeway and there is Chuck E Cheese, Apple Bees, Raising canes and other  good retail around the location.We are trying to get the latest income statements from the realtor to assess if the tenants are doing good (mainly from the bar which is occupying 50% of the space and lease coming to an end in 2022)According to our calculation cash-on-cash is around - 8.5% if the building is 100% occupied Assumptions: 25% down payment and 75% loan from the bank @4% interest rate 30year amortization Operating expenses included - Property taxes, Insurance, CAM, Management fee.Are we missing anything from the calculation ?

A few assumptions. 

I’m uncertain if I would require a storm retention pond, but my base assumption is that I would have to have one since the previous owner had plans to build an apartment complex which required him to have a retention pond.4.

There isn't a good way to know if your assumptions are correct, but while you are analyzing properties, try to use as many different calculators as you can. 

This is a 23.75% profit on my $1,000,000.Now, compare this to this DST, with the same assumptions (no rent increases, no appreciation, 6% sales commission after 7 years).

It seems my assumption that mobile home park investors/owners would actually see the forest, including the trees in regards to incorporating tiny homes.

In 2013, more bidders came on the scene and the deals were gone.Near the end, I didn't go physically inspect the condos because we had enough experience with them that we could make assumptions based on the averages.