Struggle with thin stuff all the time, it just wants to vanish on you. Dropped my amps way down and forced myself to travel faster across the joint. Letting it cool for a second between spots sometimes helps too. Gets tricky finding that sweet spot between enough penetration and just blowing a hole right through it.
Yeah, letting it cool between spots is a good call. I read that some welders use a backstep technique on thin metal to spread the heat out. Helps avoid blowing holes like you said.