Also if you choose to refinance someday, seasoned mortgage loans can easily fetch more competitve rates in the future.

But also didn't find as much volume as I find in the more active seasons.

The agriculture industry employs a lot of people in this valley, but most of these jobs are lower paying and seasonal, reducing annual income numbers.

I have a four bedroom house that I airbnb in Denver and have a friend who could live in one of the rooms for 4 months this summer (high season). 

That way it's moving season and will be easier to rent.

If we then do a cash-out refinance (after seasoning) to pay back the HELOC, would PMI go away again (assuming we are below the 78 or 80% LTV threshold)?

More season investor please correct me if I am wrong.SFH up to 4-plex would be valued base on comps.

His company doesn't do STR, but they will do seasonal.   

Right now I’m in the phase of:-building credit + savings-wanting to develop my knowledge and skills I’m in the Memphis, TN area and would love to volunteer my time and skills with investors or seasoned people in real estate to grow my strengths.

Not as awesome as the first but more relevant.There you are a successful filthy rich investor making a lil day trip through the Caribbean seas on your fancy yacht when disaster struck.