Yeah - i don't run my expensive toys in water/snow/mud. Not only does it run the risk of damaging the radio gear, it's also very hard on a nitro engine. When it gets splashed the cylinder will shrink down very quickly and cause damage to the piston and liner. I chose not to put the radio gear in...
I used a spare tank from a mbx6t and mounted it in the stock location. Seems to be working great with the tune staying consistent as the tank empties but 125cc doesn't get you very far.