Mid way through floorpan repairs, and I've had to replace a good amount of sheet metal that goes over the frame rail. What I've done on top is weld one side of the patch onto the frame rail and the other side to the other floor and repeated on the other side of the frame rail to the tranny tunnel, so basically I have two pieces of metal welded to the top of the lap joint where the floorplan meets the frame rail. Because the metal over the rail is what rotted away (strangely not the frame rail tho). I'm gonna also weld in from the bottom as well. My question is, is this a valid enough way to repair the floor and ensure it, in its floppy t top glory, is a "structurally sound" repair and I'm not just wasting time. And before anyone says it, I know my welding isn't the "greatest" but a nearly 400 lbs man standing on these welds would indicate they are good and the bead penetration is atleast passable everywhere

All of the little pieces of sheet metal welded together over the frame rail will not be a strong as the original continuous floorpan. Whether it's strong enough not to have an issue, who knows. At a minimum, I would definitely weld the frame rail to the new floorpan sheet metal. The original was spot welded. The way to replicate that in a repair would have been to drill holes in the frame rail flange before laying the new floorplan down, then plug welding the holes to the new floorpan and grinding flat. At this point, you could either use a spot weld drill bit and carefully drill only the frame rail metal and not the floorpan. Or, run a continuous weld bead along the edge of the frame rail flange to floorpan joint.

If it were my car, I would buy a replacement floorpan and replace that whole section with new and tie into the inner rocker and frame rail with new plug welds.