Not every lender offers it, but you can do an investment property reno loan and roll the renovation costs into the mortgage.

I've tried working the seller finance option, but without any success since none of the sellers seem to own their houses free and clear.

So, you have to consider the range of outcomes, their cost, and their probability.

Having a hot tub itself is what I would be looking for, even in luxury rentals I've booked for myself in the past :) My $0.02 is to opt for the larger, more cost-effective, option - which may not be the wood heated one. 

I do not recall there being a cost seg portion related to the STRs that make It better but I'm sure doing a standard cost set will also help for tax purposes depending on your goals. 

I would love to hear more info What did you learn that is not available for free on the Internet?

Cost overruns, who comes up with the money, how is return effected? 

Everything is readily available for free that I need.

I am a local San Diego investor if you have any questions feel free to fire them my way.

Any recommendations for a cost effective lawyer to start the eviction process?