If you want to get into racing too, I'm not sure if a Stadium Truck would be a very good choice, at least around here, no one runs them except for electrics. Monster Trucks, I believe would actually be the best beginner RC to buy. The question is, how much $ are you willing to spend?
Plus I doubt that the Rustler can hit 50 for the reason of how good of a tune you need., plus if you mess up during break in, it will also affect how much power it has. If you break it in weak it will run weak, but if you break it in too hard, it will blow up. Hitting 50+ will be hard to do especially if your a beginner. First time breaking in an engine may seem confusing, and may cause you to be very careful causing you to break it in weak. Also if it is broken in correctly, it will be hard to get the perfect 50+mph tune without a temp gauge. Speed isnt everything though, so I wouldnt be to worried about how fast it will go. If you can afford a Savage, then get one of those, especially since you said you live on a farm? Rustlers are good for beginners, but are losing popularity. Thats why I say go with a Savage.