If it were me in the situation I would close the split up as much as possible and JB Weld it just to buy some time.

duct tape it

an AC welder and some 6010 will stich weld it up if ya know what yer doin

Just turn it down and keep the stick close to your work. The wider your arc gap the more likely you will be to blow thru.

i've welded16 gauge with an arc. my best success was achieved by welding a little on one side, then the other, then back to the other side before the cherry dims. takes some patience but it worked for me. filled in about 1/8" wide split about 1/2 long. don't know if it was the best or most productive way to do it but i got it done.