However, I've also been reading about BRRRR investing and I'm considering the idea of doing some property improvements and doing a cash-out refinance, but I've heard that some lenders aren't doing those loans in Texas now because of the fear that the prices are on a bubble that might burst, which makes me think perhaps we could just reconsider selling in the next six months when we're ready to leave, if the theoretical bubble is still around. 

The numbers work, and will improve after I raise rents to market rate next Spring.

What makes you think they will suddeny improve?

As for the rest of your questions (2) I'm open to all asset classes with the focus being on the "right" type of asset to maximize depreciation (I.e. more value in improvements relative to land cost since it's not depreciable)

The IRS treats billboards as improvements to realty.

Each of those properties has a basis that is determined by your purchase price + capital improvements - depreciation = your adjusted cost basis. 

Does anyone who has been in this situation before have any strategies they used to improve their score while continuing to invest and use mortgages as leverage?

By leasing to one of them after 3 years I would be able to show that to the bank and it would improve my debt to income ratio.2)  The market is obviously crazy, especially in Portland, OR and suburbs surrounding so we don't believe we will get a great deal right now.

If you do not have any use for it get some capital to improve the current property or use it for the next investment! 

The deal/project may change as it progresses and as improvements are needed (ex.