Ok, this may be a stupid question but when you are connecting tube joints at a 90 degree to a main tube the 'tails' of the fish mouthed pieces will hit.
Is it important or better to remove equal amounts of material from each section or can you make the concession in one tube?
As a rule I see most intersections at the same point, meaning that the cross member section and vertical section are always together. (*making it necessary to remove stock from on or both of the tubes from the above question).
If the cross member tube is located slightly ahead or behind the vertical tube no stock would need to be remove for them to fit and hence more weldable area.
I cant see any structural advantage by locating the sections in the same place, but could see the more weldable surface being better (admittedly likely nominal ).