Having a lift and plowing and or towing

Hello, have been looking at doing a 4 inch suspension lift. My concerns are as follow:

1) I plow with my truck, I have a Blizzard 8' 6" straight blade. I want to go higher because the power hitch hits on the curbs.

2) I won't be able to park in parking ramps.

3) I do landscaping, lawn care, so I do a lot of towing, with some pretty good loads. I don't want to go down the road with the "squat" look all the time.

4) I have considered the cognito leveling kit, but for slightly more, I could get a full 4" lift.

5) I want to run 305/55/20 on diamo 20"x10" 17 karat black wheels.

Let me know what you guys think, will the lift work for plowing? How about towing?-do they have a weight limit that the blocks are good for?

Thanks, Paul