Hi John,
You are correct, make some extensions that go from Deans male to Futaba male. You can still get the 15 amps, you will just have more voltage drop through the connectors. Each connector would carry 7.5 amps at maximum load. You might see about a 1 volt drop across the Futaba connector but this is OK for short bursts. You can get 6 amps continuous to your receive with this setup (2 plugs into the receiver).