This has been broken fro a while and also previously repaired.
This is a weak point for the Scamps and kin.
I reinforced my rebuild by adding a second rectangular tube under the original and tapered to towards the front.
The added tube runs all the way to the doubled tune that the
axle is mounted on
I think the cracking in this area is caused from flexins in the door area and I would look fro cracks in the attachments from the flat tubes under the door to the fron as well. I added reinforcement here too.
PI think that what has held the trailer together until now is a few screws into the plywood.
The fish plate from the previous repair has broken out probably due to undercutting in the original thin tubing steel at the time of repair.
The added angle did not help much just focusing the stress in this area instead of spreading it out over the length of the tongue.
Here is a picture of what I cut out of my Scamp with much poor quality welding.
To repair my unit I rebuilt and extended the frame about another 18 inches to give room for a front center bath .