Looks good!. I might have added another piece of angle underneath the sill piece, stitch welded them together then notched over jack mount and welded to the upright corner. But what you've done appears it will work. I tend to overkill. How far back, looks like a 2x, go back?
Curious to see what you do for the door. Will you try to straighten the frame & use it and make a new door?
Suggestion-When you finally finish- looks like your on the downhill side-next project IMO would be supplementing the rubber snubber propane bottle attachment with something a tad more secure :)
