Gooo! I'm with BLK00TJ, that is looking like a candidate for a full frame replacement, but you maaaaay be able to sneak a repair or two on their if it's not too rotted. Start with Auto Rust Technicians. They sell all sorts of weld on parts for the frame, arm mounts etc. Here is their website: Safe T Cap frame repair kits
They sell stuff like in the pic which could solve your problem if there's enough good metal to weld on to.
I've never used them though so don't have any experience with their parts.