Ive got the midi fan size one at the moment. DOnt know what diameter the 45 size fan is but the 90 mm midi fan it was designed for fits nicely with no excess room.
There wouldnt be room for fuel over the cg. The ducting would be in the way.
THe AUW is 5.2 pounds with awing loading of 33oz/ft
The rafale i believe is larger inside, thats why that may have worked.

THere is the aeronaut rafale- 50" long and 40" wingspan for two 90 mm fans. The 45 might fit in there??? ( AUW 8-9 lbs)