Depending on when you bought your existing, some values have gone up quite a bit and you may be able to borrow against equity as an option.

A pre-existing LLC cannot, but if you want an LLC for asset protection reasons your Solo 401k can own a newly formed LLC and that LLC can own the duplex.

In that case, it may make more sense to convert existing components of a home (attached/detached garage) into additional rentable space rather than building an additional structure.

An advance against your cash flow from other existing real estate.

But, I am considering buying a home 300+ miles from me that I can use as a vacation home for myself a few weeks a year and do short term rentals the rest of the year.Question: Can I get a second home/"vacation home" mortgage (10% down) when I don't have an existing first-home mortgage? 

Furthermore, understanding the resident characteristics allows me to measure the target market and modify my investment strategy accordingly.Inspection ChecklistSituations vary from one property to the next, but here is an on-site inspection checklist to get you started:Interior Units:Inspect vacant units, including one of each finish out type (Classic, Reno, etc.).Check all down units.Inspect one unit from each unit mix.Exteriors:Landscape:Look for overgrown bushes.Identify trees that need trimming (no branches hanging over the roof).Take pictures of the following:Curb appeal on all sides facing the street.Landscape around the office and amenities.Overgrown bushes or trees.Any dead landscape.Areas that may need sod or mulch.Assess drainage:Ensure water flows away from building foundations.Check slope, gutters, downspouts, surface drains, French drains, etc.Exterior Walls:Determine the existing material (wood, vinyl, Hardie, brick, stone).Assess the condition of the walls.Note if painting is required.Take pictures of each building, including building number, each elevation (clockwise), and any breezeways or niches.Windows:Evaluate the condition of existing windows.Consider whether solar screens should be installed.Roof:Identify the type of roof.Assess its condition and age.Parking Lot:Check for potholes.Assess the need for restriping.Note whether the parking lot is concrete or asphalt.Evaluate drainage issues.Walkway:Look for tripping hazards.Assess drainage issues.Foundation/Gutters:Inspect for cracks in the brick.Check for separation in corners from fascia and trim boards.Evaluate drainage and identify poor drainage areas.Amenities:Identify possible improvements.Consider adjustments or additions that can enhance amenities.Talk to the Staff:Maintenance: Inquire about the physical condition.Office: Discuss current residents, delinquency, and potential changes to add value.Assess whether rents are too high or too low.Confirm rents and what is included/not included.Confirm other sources of income and associated charges.Confirm occupancy, pre-release, and vacancy numbers.Note: Maintain professionalism and avoid insulting the owner or broker, regardless of the property's condition.Keep in mind that investing in real estate is like solving a puzzle—you need all the pieces to see the big picture.

You need someone who clicks with you personally before engaging in a mentor/mentee relationship with the dedication and stress that may be involved.Where to find a mentorStart by looking within your existing network.

@Jonathan Krauser another thing to consider is, depending on the language of the contract, the agent/PM may "own" any bookings that exist.

Realtors exist for a reason and the good ones are worth their weight in gold] 

Sorry to be this guy... but what a client hopes or expects is a product of poor or non-existent tax planning.