Capital gains is a flat rate from 0-25%, and he cannot take advantage of any section 121 exclusion unless he has lived in the property for 2 of the past 5 years. 

Quote from @Derek Bell: I have a dilemma.

However, if you are offering a bike-rental business, expect to be changing flat tires and adjusting brakes on a daily basis.I also like the idea of using a local vendor.

There is a 20x20 or so area of flat yard in the back and then a steeper part.

if you ever needed, this resource was recommended by a contact of mine:nationwideeviction dut comFull disclosure: I do not work for them, provide any related services,  and I have never personally hired them.

I used to have one guy who did it all for me for a flat hourly rate that I could afford, but, not anymore.

Real estate as it was taught to me 40 plus years ago is a belly to belly business.. you cannot have consistent success trying to close folks on the phone unless they do not live in the market.. its too easy for them to simply blow you off.  

Are you able to sell your current property and buy a flat that you could house hack to offset your monthly living expenses?  

If the unit has these:Assume replacement every 10 years:Water heater - $900Refrigerator - $900Range - $900Dishwasher - $600Clothes washer/dryer - $1000 combinedEvery 15 years:Furnace - $2900Central air - $29003 BR SFR Flat Roof - $2100 + $300 per 3 years to coat itI annually plan for an additional $1,500 of miscellaneous maintenance expenses and $800 for capital improvements.You could probably use something like this to estimate your per-unit costs as some units might not have all the same features.  

It used to be you could build for $100/sqft on flat land and about $200-300/sqft on a slope...but inflation and also skyrocketing prices in the Bay Area have doubled/tripled that.