Yes, the oldschool solution for keeping moisture away from the receiver was to put it in a balloon and then zip tie around the servo, ESC, and antenna wires.
As for the ESC, you might want to go with the LRP A.I. Runner Reverse Digital line of ESCs, as they're supposed to be waterproof. I'm not sure what you'd do to protect the motor though.
Tamiya TB-Evolution V & TA05-R | Kyosho Ultima SC & RB5 | Associated FT RC18T