We are definitely looking at the high appreciation rates hawaii has and the stable rise in real estate.  

They could not live in the cabin but can stay long-term from November through February to appeal to winter Texans, and that is when we are slower.

It was very outdated so we are giving it a facelift and will be looking for a way to rent it out.We’ve considered retreats, STR, independent living, section 8, etc. what other options are out there that we aren’t thinking of?

As for the 2/1 unit There is a long term tenant (10+ years) that has a great relationship with the landlord (they seem to be friends as well) and has been paying rent on time ever since they have been there.

These areas may offer better long-term appreciation potential.Specific Neighborhoods:Research Local Demand: Talk to current students, university housing offices, and local real estate agents to identify neighborhoods with high demand for student housing.Check University Plans: Universities sometimes have expansion plans that can affect housing demand.

But our ultimate goal is a large portfolio of long-term rentals (100+ units).

Can they prove how long it takes to rent a vacant property?

Long winded way to say I agree with you full stop.

Long term buy and holds are typically more suited as a principal investment strategy and perhaps a Joint Venture. 

“The ability to attend to a task and stick to long-term goals is the greatest predictor of success, greater than academic achievement, extracurricular involvement, test scores, and IQ.