Julia, I agree with @Kerry Baird. Based on your last reply, it may make sense to focus more on DSCR than DTI, which may very well free up some or a bunch of your capital. Then, it's a whole bunch more about the property or the portfolio and not just you and your W-2/1099 income. At 30% - 50% down, everyone runs out of money at some point. Usually, this means working with a more nimble portfolio lender vs. a regional or large bank. I have no experience with the lender Kerry mentioned, but that one would be a good place to start. If interested, another thought is to ask members of your local Houston REIA group, because I am confident you are not the only investor who has run into this problem.
I also agree with @Guy Gimenez, especially on the topic of having your private mortgage buyer sit down with an RMLO - this process should be documented and you should keep copies in your property file. Though states can make it more onerous, this is not specific to Texas. I mentioned this in my first reply, but didn't really elaborate on why this is such an important step. Per the Dodd-Frank Act, or whatever modified version we are still living with today, it can be construed as a requirement, despite the fact you may only do one of these each year, or even less often (rules are different if you do more than 4 or 5 of these per year vs. just one), but the buyer needs to understand what it takes to qualify for their take-out loan prior to the maturity date of your balloon (assuming you impose one). They also need to sign up and pay for credit counseling - another part of the original DF Act.
In summary, all the steps you and your buyer take in the process between contract and close are incredibly important to protect not only you, but the buyer from themselves. Especially important given you are licensed. You (we) have a target on your (our) back already. Doing private financing just makes the target larger. So, don't shortcut the need to treat this transaction exactly the way you treat it in your brokerage business; state-approved CBS, dates/deadlines, prelim title, inspections, survey, insurance, appraisal, title, RMLO process/credit counseling (takes place of loan approval), then on to title co escrow close.
Finally, as @Guy Gimenez also mentioned, you absolutely should use a note servicing agent (think "arms-length"), which very nearly always is covered by the buyer (both one-time and recurring costs). FYI - these "qualified intermediaries" are not always easy to find, but you can ask your title co or your real estate attorney for references, or post the question on your REIA's website. Last one I used is called Evergreen Note Servicing near Seattle, NoteCollection.com.
Personally, for the time and risk, I would rather do commercial (5 or more units), or earn 8%-13% doing multiple, short-term, real estate crowd-funds, or both, and not worry about it.
I will say this though, of all the private funding type deals I have done since 2004 (50+), I have had the most success with seller carry wraps (all of mine had underlying mortgages), especially when compared to my second best - Land Contracts (contract for deed) and the ultimate bottom-of-the-barrel play - lease options. This said though, compared to crowd-funding, I will NEVER do another seller wrap again, but I will remain a happy landlord and have no problems with tenants and toilets!
Have fun with it!