Reposting:
Use Your Reamer to Make a Matching Tenon Cutter

I did manage to get all my workbench base pieces fitted and dry assembled.
One trick I used was chalk on my tenons for fitting. I chalked the tenons once they start to fit but get stuck. When I slide the tenon in, the areas that are sticking rub the chalk off.
And that’s .. where I focus my trimming for the perfect fit.