And you heard that from a bonafide expert on the topic.I should have read that first and saved time.
It's impossible to meet those specs.
I threw together a couple of switching supplies using the LT1171; schematic & simulations shown here:
Efficiency can top 90%, depending on Vout & load. The expensive part would be finding a suitable 30v-36v input supply capable of cranking out the amps. The nice thing about the two is from a single input, you'd wind up with both a positive and a negative supply from 1.2v-30v and -1.2v to -30v; you could use an LT1170, LT1171 or LT1172 depending on how much current you wanted out.
On your variable supply - you will run into heating problems when supplying moderate to high current at low voltages; your heat sink is small, your project box is sealed, plastic, and there is no fan & vent holes to get rid of the heat that will build up. It's hard to kill an LM317, but you will probably find that it will cycle on and off due to it's built-in protection features.