Hi UCB - To address the weld distortion issue you could soft solder the parts together. There are many solders in the 200-250degC range that would provide the required strength. At this temp there's hardly a colour change, a propane torch will do the trick easily. The loads in the structure are nowhere near the material strength due to the large stiffness requirement. We are looking for joint stiffness and efficiency with no distortion, metal to metal contact provides this. Silver solder definitely provides the answer, I do this alot. But softer solders will work and are cheaper and easier to do due to the lower temp. This also allows very thin things to be connected together easily... Cheers Peter

https://en.wikipedia.org/wiki/Solder_alloys