Selling land to reduce your debt is a clever move.

I'm currently looking for opportunities to increase my reserves and move into bigger things.

Buy and hold is a good strategy.Theft has been an issue during the rehab stages until someone moves in.

I currently work for the US Coast Guard and will be moving to the Philadelphia area in June 2024 with my fiancee.

And as @Jay Hinrichs says, the market needs to be right for this strategy and you need a little "jingle in your pocket" ;) Most the time you are bringing a seller current on payments, providing moving expenses, and tackling deferred maintenance/updates - or all three on sub to.

I'm trying to decide if I'm going to continue in St Louis or move on to spread my portfolio across multiple cities. 

You need to answer these basic questions first before you start thinking about taxes, corporate structure, or anything else. 

She originally moved in 6 years ago as a couple w/ 2 children,  they got a divorce last year and she stayed in the house. 

If you have a track record of success this may be alittle easier moving forward but lenders like to see your money in the deal, and the more of it the happier they are.

I think it might make more sense for me to continue to rent my current apartment due to the conveniences and being able to walk to work versus moving into one of the units in the multiplex as I had originally planned.