Toggle circuit with 1 x NAND, OR, and NOT gates?
A you say you allow diodes and transistors, why not place a 5pin SC70 package with a single D register from Texas Instruments. It uses 2.2x2.4 mm. 

I think these are called 'tiny gates' as they are for exact the situation you are in: you need one/two more gates to finish the circuit. 

This is the search page for 1 bit registers.