I always get a good laugh reading the responses to a question such as this one. There is absolutely NO reason why you cannot pull a 4 place enclosed with 4 sleds with a 1/2 ton truck. If you are feeling really dangerous, go ahead and even throw a 5th in the back of the truck. (caution may slow the truck down!)
I really don't understand the mentality that you should be able to accelerate like you are unloaded when you have a trailer. Uh-oh truck is slowing down, must need a diesel. Will that weight slow a half town down, yes. Will it downshift more, yes. Will you make it there just fine and be able to go snowmobiling, YES!
If you do other heavy towing, 5th wheels, construction equip etc etc and you need a diesel for that, I understand. For those who feel the need to buy a diesel to tow a 4 place snowmobile trailer irregardless of the distance, WOW. Do you realize most people uste to pull their steel trailers and sleds around with cars??