Howdy, Joe, and welcome to the forum.
As to using your router table as a jointer, I think the trick is to apply the same "tuning" issues encountered with jointers. That is, make sure the outfeed section of the fence remains parallel or co-planar to the infeed side, and the trim cutter is precisely aligned with the surface of the outfeed segment. Otherwise, one is replicating all of the problems associated with poorly tuned jointers.
One approach is to "shim" the outfeed segment with a sheet of material that is of uniform and known thickness. That might be 1/16" or even 1/32" thick, which then becomes the depth of the cut, similar to the settings on a jointer.
If the router table split fence is constructed to be in two layers, one "fixed" (the part that actually attaches to the table top) and one moveable (the surface against which the work piece glides), the "shim" can be placed between the layers on the outfeed section.
Of course, all of this assumes that the fence is precisely square to the surface of the router table top.