Now I have a fence that I can adjust side to side, as long as it's a straight line I want to cut. Did this twice, so I can run the router between them and be sure it won't jump or bounce out of the path I want. I had initially set it up on 2x4s, but with the router riding the aluminum clamp, and the 2x4 being higher than the neck, the bit wouldn't have reached deep enough. So I cut two pieces of 3/4" ply wood that I had left over from building the bench. Once I did that, i had a different issue. The knob on the router was bumping the rear fence. So I ripped an inch off the top of that.....
on 2x4s:
I checked the level-ness of the neck, and the 2 rails using the bubble level app on my phone, so I know it's extra precise.