Joem,
I think you're saying your torch is the type fastened to the small bottle so that the tank has to tip when you point the torch down. I expect most professional plumbers would use a propane torch that has a hose so they don't have to deal with that constant changing of flame when they tip the tank or perhaps the newer bottle ridgid torchs perform much better than the old one I have. I'm familiar with Steve's videos, but in the ones I've seen he used MAPP or OxyAccetylene. The insulation you are doing is probably the big key to your success with propane and I'm now confident that my swirl propane torch with tank, regulator, and hose along with some insulation will do the job. Also I'll make sure the gold is really dry or let boraxed dish cool before loading it.
One more question. In Steve's videos he seems to be in a big hurry to grab that hot nugget and quench it in water. What would happen if it was simply left in the melting dish? I expect the borax might glue it to the dish.
Thanks for your help,
FrugalEE