Has anyone had any success using Airbnb income for a loan application?

Your options are limited with that much first mortgage debt on the house.

Where this gets tricky is that FHA does have county loan limits. 

Here are the numbers I've calculated  based on 80% refi of all 3 properties, at 30 years, at 5.25%:Item                              Current                 Post-RefiCash available         $        0                   $300,000 +/- Cash Flow/Year       $   65,000              $  52,000 +/- Re-invest $300k from Cash out as 20% DP on more properties (there's an even better way than this too)& using the same ratios of ARV to NCF, you could increase your NCF an added:  $78,000/year; to $ 130,000/yearYou are sitting on a Gold Mine here, and you're thinking like a "homeowner"...not an investor...although you're not alone.Your Options:  Limited by the maximum Cash Flow from existing properties after complete payoff Max CF/Year                                                                                    =  $   95kCost to do this (pay off all mortgages using your cash)          =  $  456kNet result                                                                                        = - $ 361K  (that's a loss)REFI ALL Option:  Limited by ???????                                                                                                             

The beauty of Seller financing is that you are not limited by convention, but rather are limited to what you can negotiate.

It also limits how often you can claim this exclusion to once every 5 years (instead of 2).However, it is politics so who knows if the tax reform bill will become law.

Or is the rental season very limited?  

For example very specialized TI work specific to the tenant could limit the potential future tenant pool for a building and therefore increase the cap rate whereas generic office space closer to "market standard" may decrease the cap rate.I also agree with @Peter Bowen, the actual cap rate for the building will be set by the market.

Hi Lorenz,A limited cash out refinance into two 30 year terms might benefit you, however make sure to consider closing costs with this type of transaction.

Plus the limited rental options make 11 seem low a little.