wow, saved by the axle, bunks sitting right on the axles - that was one mean azz'd bump you hit
There's more going on with that broken member than rust. The break is way to clean and vertical - like it was jointed.
after seeing those pics no way if it were mine would i put a boat on that again and tow it dont care how good a welder he is there is more rot then u see now somewhere. not so much for losing the boat but the guy behind you when it lets go.