In addition to my full-time role as an engineering manager, I’m building my real estate business as a side hustle with plans to grow it further.My current focus is on assisting first-time homebuyers and investors, but I’m always eager to explore new strategies and opportunities.

A 10-15 year payback very well might be a MUCH better investment than you are making it sound like because the price of energy goes UP in addition to the lifespan of the system being longer than you suggested. 

Something else to consider is that once these properties are paid off, you could cross collateralize to purchase additional properties that fit your buy box so that you may not need to bring cash to the table for a down payment.

That said, if you can comfortably handle the additional down payment and monthly payment consequences of a higher purchase price (and the lenders agree), and you have a few different good options with the property then it could be a wise investment.By a few good options . . . you want to have some exit strategy other than STR that will work in case the something happens to make STR uncouth in your area. 

@Renay Reese my employer doesn’t want us to carry but, I do because I work near the airport and people are crazy around here...

Additionally, there is specialized equipment including diagnostic machines and hydraulic lifts.The use of the accelerated depreciation strategy helps real estate investors to reduce the tax liability immediately which therefore increases their bottom line due to the offsetting of income.

Read a few booksz like Brandon Turner's, and you will see how your VA loan and a few time tested strategies can be employed.

Solo 401k requires self employment with no full time employees other than you and a spouse.  

Additionally, since you need to replace your vehicle soon, you should consider how that $30k purchase fits into your overall budget.Take a close look at the current housing market in Orlando, where prices are around $400k for decent homes.

If the purchase price is 70% of the home's final sale price, what portion of the additional 30% is the $ spent on the flip and what portion is the average net gain?