Trailer leaking in front corners

How old is the trailer?
Probably get away with just a weld patch.

 

That's very thin aluminum... It could be welded and patched... But odds are it will reappear in a very short time right beside the welds. I'd say its time to look into a new trailer.

 

Trailer places like utility sell this tape. It’s pricey but works very well. On one side it’s shiny like aluminum and other side is extremely sticky black rubber. The tape is pretty thick like 1/8”. I would just buy a roll of that and stick it on there. Trailer shops do this 99% of the time.

Here’s a link to what I’m talking about.

4"x50' Aluminum Heavy Duty Foil Adhesive Body Repair Tape Trailer Roof RV Truck

 

Here they treat it like a roof patch. Flashing, pop rivets, and caulk seals it and doesn't look too bad.