All electric motors are waterproof(except maybe sensored brushless?), so no worries on the motors. With the servo, I would either use a traxxas waterproof unit or smear some silicone type sealant around all the seams of a non waterproof servo as well as putting some grease around the output shaft to keep water out. And as for the receiver, I would find a traxxas waterproof receiver box from a stampede, mini revo, or any of their waterproof models and mount it on the truck to keep your receiver good and dry