An addendum is sufficient.

Can you afford the downpayment, brrr costs, keep money in the deal and have sufficient reserves for both properties(i.e 2 years of vacancy/lead times, 75-100% of capex, 3-6 months of random ********?

do you think 1 Gbps is needed or is 500 Mbps sufficient?

Your existing REI background will be sufficient for any lender.  

Having contingency plans and sufficient cash reserves is crucial for navigating unforeseen challenges.Hope this helps!

or is email sufficient?

What I mean is if it's already a rental with most of the basics in place, it shouldn't matter if you spend 3k or 25k, if it cash flows sufficiently.

I think many people have sufficiently answered your question, but here's an article that you may find helpful regarding STRs to determine if this is a strategy you are interested in.

An email marketing funnel for re-booking is nice, but it's barely keeping up with the year over year decline in rents due to saturation (quantity saturation AND quality saturation) and shifting travel trends.  20 years ago your hot tub made your listing an all-star. 

I ended up investing in 3 deals with Western Wealth Capital in 2021. 1 is underwater and they couldnt raise sufficient funds for capital call.