It also happens to be in a cul de sac. 

But she has a daughter who is living in Delaware.

Do short term rental guests in Delaware have any sort of squatter's or tenant's rights in Delaware such that I should try to avoid a certain length of stay? 

She moves quick too none of this la de da.

If you're working with a 1031 company, enlist their help to make sure you're considering the important variables..Many of our past and current clients have/are invested in Delaware Statutory Trusts. 

The house would then be a de-facto multi-family unit.

I'm the owner's nephew and de facto "computer wiz" because I am relatively savvy,  but I have never used any property management software before.

There is a de minimis exception.https://www.law.cornell.edu/uscode/text/26/7872$10,000 de minimis exception for gift loans between individuals(A)In generalIn the case of any gift loan directly between individuals, this section shall not apply to any day on which the aggregate outstanding amount of loans between such individuals does not exceed $10,000.

I know rhino is used and they charge a monthly fee to tenant, but is none stop through out the lease and most clients don't want an extra payment. I found The Guarantor which not only offer a deposit insurance bond bu...

Quote from @Candice De: I flipped my first house this year in Denver - mid-pandemic.