Personally, I've seen a 10%-20% dropout rate from soft commit to funded deal, depending on the new/repeat mix. 

I would raise your soft costs to 5%.Are you managing it yourself?

With the planning and building dept's heads deep up their rectums plan for 4 years to get your permit.Is $400/sf including the soft costs or is that just the hard costs?   

Tenants have liked that it's much easier to keep clean, and they can put an area or throw rug down if they want to for softness/color.

I had a lender say he would fund everything with upfront costs of underwriting/appraisal and soft costs.

Loss of Rents or Soft Costs coverage should you have a covered loss.

well this is complicated and highly unlikely anyone can help you on an internet forumyou don't say what jurisdiction it is.there are about 40 steps to get a project approved.5 acres of townhouses might be 100 units soft cost might be 300k or more up front. financing to build 20 mil or more  5 million in cash equity probably needed to pull that off. to name just a few of the 40 things that need to align to have a successful development

@Sam Casper I dont think you can do this in most jurisdictions, however I think you can do multiple, within soft stories in San FranciscoWhat city are you looking at building an ADU? 

is the rental market soft or strong?

The 30% represents what I call your soft costs and you profit.