I will bet those little tires will not carry a full load.
Maybe a couple of blow outs, leaving it on the side of the road and finding a burned to a crisp pile of metal will make him rethink this crap.
While I get what you're saying and being a little facetious. The detail side of me calculates 110 gallons (IF he fills it), @ 6.3 lbs per gallon is "only" 693 lbs + maybe 75 lbs for tank + maybe 500 lbs for trailer is only 1,268 lbs...those two tires will do fine. And, I didn't even get into how far forward he has the load, at least 20-30% is on the hitch. BUT YES, Stupid. Carry on.