After the roll bar was complete I built the mounts.

I had to trim the bottom of the rollbar on the aft side almost to the bottom of the hole to get the proper height.

This pic is before I trimmed off.

This bracket went on obviously before the rollbar was closed.

You carefully fit the rollbar and its mounts on top the longerons before drilling their mounting holes.  These

are all preliminary fit photos.

Still trimming to get the proper fit and height.

Made the small brackets to mount the top rollbar support.