You want to use dry yeast or liquid?
Traditional dunkels are lagers, so you'll need to account for that when fermenting (you could lager in your fridge, but you'll need to turn the temp up during fermentation as most fridges are quite a bit lower than 50F). Whether or not you can stand your leftovers at 50F for a week or so is up to you.
The sacrifices we make for beer...
If using a dry yeast, I'd go Fermentis W34/70, if using liquid I'd go with either Bavarian Lager (Wyeast 2206) or the Munich Lager (2308)
You could use an ale yeast, but you'll need to be careful not to pick one that attenuates too far (like US05/Notty), and ferment it cool so you don't get weird esters showing up. Something like BRY-97, Fermentis K-97, Wyeast German Ale might be a good choices, just know that some of them are pokey yeasts that takes it's sweet time showing up or leaving the party if ya dig.
Here's a link to a BYO article that might help:
https://byo.com/stories/item/578-dunkel-style-profile