All of our self-storage run at basically 100% occupancy except for our most recent addition. 

Excess depreciation could be suspended as a passive loss unless you qualify as a Real Estate Professional (REPS) or materially participate in a Short-Term Rental (STR)—which would allow you to use the additional depreciation to offset W-2 or business income.

Additionally, it pretty much the 1% rule as a LTR and would absolutely kill it as a MTR/STR!

Then when you sell another 22% and 8% on that gain?

(replacing the original HELOC debt) However whether the interest for the  additional $200kish of loan  will be deductible will depend on 2 things: -How were the renovations paid for?

If you paid under $230k, you’d save $30k in federal capital gains taxes and maybe another $15k or more in state income taxes.

the majority of even my national users are looking to keep cash in reserve and as such are looking to landlords to finance that TIA as additional rent at a return premium and then that extra rent bakes off in whatever term is negotiated. 

If you just take the 13,835 financed at 6% you are adding 83 dollars a month. so a double whammy.Now, lets consider if rates drop to 5.5% in 24 months (not a prediction just a what if) and you could have refinanced at a much lower costs then the above scenario in what you paid in pre-paid and additional interest. on the other hand, if rates for your same scenario after your 5 year payback period is 9, then you will have an asset with a much lower then current market rent.  

Highest number of units without getting into commercial buidling codes at 4 units you have additional engineering requirements. 

For comparison, I just completed two new build duplexes in a flood sone in central Houston using a builder for these and my Hard + Soft costs were $149/ft. the only additional cost to factor in was the land.