That's reasonable...main thing is you're putting some kind of weight in or on those rear tires.
BTW, Rob...I might have missed this, but did you get a ballast box with your 3320?
I gave Dawn my I match for her 990 but she bought her own BB. I had one of my own from the 2720 and bought a new I match. Right now the 485 hoe is on the back and things are very stable (It's 1500#). I haven't had much time to play with the 3320 yet but I did try it on a couple of 10 to 15 degreee hills and it seems fine. That's with the tires in the narrow position. I do like to keep a lot of weight on the back and usually I put the 5, 42 lb. Deere weights I have in the BB when I'm not using them on the front for bush hogging.
Rob