Hard money lenders, traditional lenders, private money lenders... 

I'm super happy with BP as a great resource for more traditional real estate, but I'd like to do some exploration into land hacking as well.

If you are seeking a more traditional DSCR type loan, then typical guidelines apply; Credit, Liquidity, and Experience. 

. - Long term residential rentals: Primary interest to start building.  

They have told me that the primary reason they do this, is to prevent their tenants from purposely trying to sue them.

Roth or traditional or combination.  

With STNL if you have about 10 years left on the primary lease you tend to still get good debt on the property.

I work with a lender that allows that as long as we can document some explanation that the borrower doesnt plan on occupying the home as a primary residence.

I’m guessing the ski community is highly seasonal and has deep-rooted family traditions of return vacationers.

It is typically your primary job.The 40 hr/week W-2 worker is going to have a hard time convincing an IRS agent they are meeting this threshold.STR loophole is a better path for my friends in this category.Once you finally cross the pro hurdle, you're not done!