As stated, ASME tanks are not recertified for RV use. One and done. But a certified filler, like me, can refuse it just for safety's sake if it's that bad.
For DOT cylinders, there is a chart (in Texas anyway) for how big/deep dings can be. So wide can only be so deep. I would apply that chart to the ASME tank just for comparison. Most likely, just sand/brush it, paint it over.