I have to agree with the previous post. I would go with an SCX10. It is very capable and can still be made to look extremely scale with a little time and effort. However, a note on the "sealed" bearings....you will still need to take the seals off the bearings and clean them out with some motor spray, then re-lube them. I've had mine in water and mud countless times and the water does still get into the bearings. I found this out the hard way by getting my truck wet, then the next time I went to run it one of the bearings was almost completely seized with rust. Another note...when you put your axles together on any truck that will see water you'll want to seal them up good with silicone. That will help keep water out so you'll have to strip your axles down less often to clean and grease.
You can seal up the RX box on the scx10 pretty easily but I wouldn't reccomend putting your ESC in a box like that because it could overheat. I use a Novak Rooster crawler esc that says it is "splashproof" but I've had it completely submerged for several minutes at a time on numerous occasions and a drop of water has never gotten inside the case.
As for waterproof steering servos, you can use a traxxas waterproof servo...but the plastic gears in them don't last very long if you are hard on it. I dip my servo's in plasti-coat, then put an O-ring behind the servo-horn to help keep water from getting in around the splines. It works pretty well...but after long periods of being submerged I still notice a little water in mine from time to time.
Hope some of these ideas help.