That's unlikely - you won't get the integrate mission unless you own a territory adjacent to them. And owning Franken would just mean Bavaria attacks you directly rather than the Palatinate. If you're not willing to build up to beat the Palatinate you should probably just take some cash and peace out.
My opinion is to instead vassalise either Cleves or Saxe-Lauenburg - the former has fewer potential threats around it, but the latter is easier to reach and more useful for forming Germany - and use the slight buff to forcelimit/income to work on your next target. Diplo-annexing the OPM without the mission would only give you one unlawful province, which shouldn't be too much to bear.
Oh right. I forgot about Bavaria.