You just need to stand out from the crowd.

CA has a law specific to 1031 exchanges, if you exchange a CA property for an out of state property and you later sell that out of state property then CA may assert the right to claw back (tax) the gain attributable to the CA property that would have been realized if it had been sold rather than exchanged at the date of the 1031 exchange.In this regard you may have annual reporting attributable to the out of state replacement property so CA can track what you have done with it.

We also purchase with no inspection or contingency periods; which also makes our offer stand out better.

We've grown our portfolio up to 22 units and have a mix of tenant payment methods: manual cheques (fun), e-transfers, bank counter deposits and some have done PADs at their local branch.Our challenge has become with t...

As far as beating out other offers, you can always write the offer in a way that helps your stand out with using a VA loan, adjust some of the contingencies, don't wave them, but adjust the time on some of them.  

Cash is king, but some people have special circumstances (such as rent back or other timeline things) that can make your offer stand out if you can accommodate them.

And if as you say most won't take the time, then that makes it much easier for those that do to stand out!

For ADU's - I've seen older posts on them being attributed limited value despite the additional sqft, bedrooms, bathrooms, etc. they add to the property, but the methodology seems to be geography specific.

The rental market is hot right now so it probably wont matter, but in normal times, I like to pay a bit extra to get a 2-tone paint (tan/white trim) to make the unit stand out a bit, but again, just preference - I don't think either get you more in rent. 

Really stand out and change the local Airbnb game.