Best strategy to lower DTI for a mortgage loan

[Nico Ferreri]

Hello BP Forum! I'm pretty new to this industry, but have been soaking up a ton of info all summer reading BP books and listening to podcasts. I have a few personal finance questions regarding my student loans and my goal to lower my back end DTI. Im 24 years old.

I have about 100k in student loan debt between my private (4.2% rate) and federal loans (I wish I made a better decision with college but cant change it now!) My monthly payment in student loans for the foreseeable future (10 years) is going to be around $800/month. I have about 26k in my savings account at the moment and around 7k in the stock market. I'll be making around 55k with my W-2 teaching job. In summer 2023 when my girlfriend and I move to the city that she chooses to go to PA school, we will be looking to purchase a small multifamily property and house hack. My only worry is that with her having no income while in school, my DTI will be too high to get approved for an owner occupied low downpayment loan. My estimate is that my back end DTI will be around 50%. I know the Dave Ramsay method is to pay off debt as fast as possible, but then again I've heard investing that money instead is a better option. What should I do? Use 10-15k of my savings and take a chunk off my student loan debt? Refinance private loans to longer term period so the monthly payment is lower? How much of a factor is DTI? Especially if I have a good credit score, I'd have around 30-35k savings by next year (and my girlfriend will have around 30-40k in savings as well. Do those compensating factors outweigh a bad DTI? A

Any advice would be greatly appreciated!