Many moons ago I made one of these for one of my trim routers and it has gotten a lot of use. You can even use it to level ruff wood but I digress.
However the SO has some other factors which make this more of a test if it can be done then a surefire solution to solve those issues. And no it is not going to be used to get a flat surface on ruff wood, well at least I don't envision that.
As an over view this is the general idea of where I'm coming from.
The basic idea is to have supports on both sides to keep the SO level and not dependent on the work piece surface to support it or keep it flat and level. The span is somewhere near 2 feet give somewhere in the 10" reach for working on the project.
One of the things I think it will need is some support to keep the weight of the router and downward pressure from bowing things at that distance.
At first I was picturing use some U channel or the like. After thinking about for a while I came up with an idea to use t-track. In this case the function of the t-track is not for mounting things but for support. In other applications it could do both. We will get back to this in a moment.
The basic idea would be to attach the SO to the platform and as luck would have it the SO base has two threaded locations that can be used. There is some other oddity about using the touch-off but that is more of a detail for the SO people so we will let that one slip by.
In the sketch you can see that base plate/jig interfaces is, it is the large square towards the middle. We will not cover those details either since this is not about those fine of detail on the project.
Now we can get to what is nearly the final design. Keep in mind the use of the mounted track is intended as only a support in this design, other times the actual function of the track can also come into play.
Now here is the part where you need to pay attention.
This is track I own so if you happened to have some other brand or style this might not work as well or at all. The base of the jig is counter bored for the heads of the fasteners and through hole allow the fastener to come from the bottom and go through the tracks holes and a nut can be added.
Not breath taking or new but I like the application of hardware in this manor.
Here are a couple of pictures:
The method of attachment should allow 1/4" t-track hardware to be used. If so then this can have a lot more applications.
I'm looking forward to getting this project underway and will keep you inform as to what I find out.