I had one years ago for just this purpose. It was simply a sink cutout from a laminate counter top. I routed out a recess to mount a router into and clamped it to the underside with some home made brackets. I did find it necessary to reinforce the top with some perforated metal angle to keep it relatively straight. This was preferable to a thicker top due to weight.
I installed a straight L-shaped hardwood fence on it by attaching the outfeed end with a pivot pin that I cut off from a hinge pin. The infeed end was simply clamped with a c-clamp. I put some threaded leg plates on each corner and used some old furniture legs to lift it up to allow clearance for the router motor.
I suggest a tall fence if you think you will ever need to run material through on edge. Just remember it doesn't have to be elaborate to be effective. If you are using it on a job site, chances are you will be doing relatively simple operations so, KISS.
Good luck with it.
"The difficult we do immediately... The impossible takes a little longer" - Grandpa
Don't worry about nothin', aint nothin' gonna turn out right anyway" - Dad