This is my sled jig. Basically it is two L channels on each side. The channels keep the sled about an inch above the table. The risers are also spaced an inch from each edge, to allow the bit to hit the edge of the table, but not ruin the riser. The jig is made from pine, with the exception of the rails on the sled, I used some scrap red oak to give it strength. Even with the rails, you don't want to push very hard.
It took me approx five hours with a 3/4 inch strait bit to do the entire table. The bit was almost new, and was dull by the time I got to the other side. The hardest part with the jig is to not cock the router, or push down (at all!). Make sure you lightly clamp the sled on each side. You can clamp it, make a three or four passes, then move the jig and clamp it again. The rails were held on with pipe clamps.
I used a square and a caliper to make each L channel height as equal as possible across the table. From there, find the lowest spot on the table, set the bit to 1/16 inch or less below that, and then start on the table edge. If you don't find the lowest spot the first time, be prepared to start cutting all over.
I hope this helps some people that don't have a wickedly large planer or drum sander.