I haven't purchased this way before, and unless you can gamble a bit of cash without having a contract, I wouldn't suggest it.

They may want to gamble on someone else not knowing the 20 year old HVAC, but as you mentioned, it's going to come up during the inspection.  

Fortunately, the calculated gamble had paid off.

I don't see huge upsides as there is only a few years left in the up swing and after transaction costs, it's not that fruitful to buy now and hold for another 5 years or so.Also, I'm in earthquake country and insurance is a gamble at best as they may deny a claim.

That said my STR is not somewhere that a cozy authentic wood fire would be expected.

Being a middleman- Realtor, contractor, ect -and get paid off the "investors" gambling. 

That will be authentic, and may work better than computer-generated mail.And the guy who runs yellowLetters.com, Michael Quarles, I find to be very sharp.

"They are intrigued" There are lots of authentic mail pieces you can use including stationery, that has choices of return labels, or hand-written. 

Important to note: This was a big gamble but a very calculated risk.

A gamble.