IE in many areas you have historic platted lots  say 25x100 and you had one person buy say 4 lots.. well the assessor to make things easier on their office would combine the 4 lots into one for tax purposes ( common) at least out here on the left coast. 

We were thinking of creating a joint bank account which we can combine our cash together and use for future traditional rental properties as well as Airbnb/Verbo properties.

If you combine all three you are bent over the coals. 

B/C in CA HML are generally 400 to 2 mil or more its rare one investor buys a whole note.

I’ve considered combining two bedrooms into a master suite which should be cheaper because it wouldn’t add square footage but not sure if a 2/2 is much better than a 3/1 in the market. 

If they want a quick close, your lender should be able to advise on how quick they can close.Remember though, it's a combination of all the terms that makes an offer competitive. 

Both combined should give the feel of more user space encouraging people to spend time outside.

I do these for investors on small balance deals as my normal course of bizz I rarely do a loan OVER 100k..

I have over 12 months of cash reserves on all properties combined.

Purchase price: $765,000 Cash invested: $120,000 This Mixed-Use Short term and long term apartment building was a rare find!