Will doubling thinner wire in lieu of thicker wire work?
Yes, keeping in mind that the rule is that an increment of 3 in AWG numbers represents a halving of the cross-sectional area of a wire. The current capacity is directly related to that area.

This means that to create the equivalent of a wire of AWG(N), you need two strands of AWG(N+3), or three strands of AWG(N+5). Three strands of AWG(N+4) gives you some extra safety margin.