I am exchanging the telescoping beams of a Supercat 20 with solid ones. After long sourcing on the local market, only two sections seem available options:

(6063 T5)

rectangle 'tube' 100 x 120 x 2 mm wall

round tube 100 dia x 2 mm wall

round tube 100 dia x 7 mm wall

I intend to use the 100 / 2 round tube as frontbeam as the round 7mm section seems far to heavy.

I am puzzling with the rearbeam:

I would appreciate to raise the rearbeam more from the water. Using the rectangular section (green) and a 5-10 mm thick aluminium plate (grey) as well as a half section of the previous round section (yellow), this could be achieved quite easily. The question would be if the welding (red) would be strong enough (a suitable method in that area) and if the platform would increase in stiffness or actually become weaker as a round section could deal better with torsion? Any comments? Thanks!