Personally, I use the "sheet metal with folded edges" function, it's fast and SW does "everything" the work. It remains to be seen what finish you want on your part, we guys in the workshop are very good at making junction welds "disappear".
I didn't do it on this example but for the rounded corners you will have to go through a removal of material, the leave will not work.
Quick question: Can with this "folded edge sheet" method, you can have wings that are not the same size. As in the model posted by the applicant and where you can see the welds too well, there are the side wings which are not the same size as the others.
Can you post your file so that I can educate myself ;-)