Just as a matter of p-aminophenol interest, I have a U. S. War Department Technical Manual of Basic Photography dated July 1, 1941 that lists a Tropical Developer:

Water (at 125 F)..............96 ounces.
Para-aminophenol hydrochloride.....400 grains.
Sodium sulfite (des.)....................6 ounces, 200 grains.
Sodium carbonate (des.)...............6 ounces, 200 grains.
Water to make 1 gallon.

This translates to 7, 50 and 50 grams per liter. It was to be used full strength. Adding the sulfite should result in precipitation of the p-aminophenol base, as it does when making Rodinal, and I suppose a paraminophenolate is formed to make it soluble as the carbonate is added.