Onto the chassis rail today...
Bit trickier in the end with wind blowing away the welding gas and all sorts of weird angles to get the torch in the right place but I’m happy with the weld quality. 2mm is much easier to work with than the 1mm I’ve mostly been using so far. After a vacuum down the rails I treated the whole area with rust converter and zinc primer. Used some cavity treatment spray further down the rails where I couldn’t reach.