The range of adjustment depends on the feather board. A TTrack on the fence should be high enough so you can attach a featherboard vertically. I think it is worth the effort to build a fairly tall fence or even split fence. There are featherboards meant for installing on the fence and they are not as tall as the most common ones. Pix of pair of featherboards on router table, holding small piece down and to the fence. Also a pix of shop made featherboard that uses a star knob and Tbolt, on a table saw but usable on a router table IF you cut a slot for the bolt to fit on a slot at any distance.
The more I do, the less I accomplish.