Nate - like I said I do these open parlays all the time. Plenty of times I find myself in these situations and I always check all my options for hedging and potential games I want to play.
If I was in your spot I would wait for a MLB game with a huge favorite like OAK -200 vs Hou. you take Oak on ML in your parlay and you can hedge it by taking the Hou ml dog in an open parlay..a small one though like 4. If Oak wins then you have only 1 spot to go and if they lose then you have another parlay pending with Hou as a big dog.
Otherwise I would just wait it out and pick a very low line that has high chance of winning. You have gotten this far so don't pick something with huge ML when you can find a better spot with a lower line later on.