We were planning $600/mo mortgage payment, $100/mo insurance & $100/mo taxes - balloon payment in 5 yrs.We are providing $5k to pay back taxes ($4k), back hoa ($125), pump septic & grease trap clean out ($225), survey ($600)  & our children are paying closing costs ($1500).Deal stalled as owner backed out on seller finance.Suggestions?

Ordering a full topographical survey of the property (which will be required for future development and application processes anyway) will give you the ability to show engineering/design groups what you have, and they can give thoughts and bids leading to a site plan. 

Generally, lenders are going to do the rent calculation based on a long term rental either based on the actual rent on the lease or the projected rent from an appraiser's rent survey. 

Although we weren’t changing the exterior, we were asked to provide a survey of our property, elevation drawings, stamped FAR calculations, and sat in front of the city councils to obtain an approval (the special permit).

Encinitas is cheap, City of SD is expensive, Vista is brutalRequirements: Stormwater management, surveys, soils reports -- these are big ticket items that vary a lot by city.

Can you do a light survey of the people who have looked and did not submit an application to see why?

Google again and replace "inspections" with "survey".The property does not need to be ADA compliant unless you have a disabled tenant.

The problem is when we got a survey done for the buyers, it showed that a barn mostly on our property has a corner sitting on the neighbor's property.

Also look into the Milestone Survey (law for FL when condo building collapsed in Miami.) 

Title insurance and surveys are a must when buying.