Is 1/4 " Stainless Steel rod OK for the stringer? (For trappezing, not for using a jib.)

How does the vertical post nest on the front crossbar base? Is it attached as in rivets.

I am planning on welding a piece of SS to the base of the 5/8 " SS vertical post to spread the pressure over a wider area. The base will be bent somewhat to follow the curvature of the Crossbar. I will probably put some epoxy on the mating surfaces to reduce the likelihood of galvanic corrosion.

Also what is the standard post length from the crossbar to the rod (stringer)?