I don't think the offset is causing your vibration. I put mine in with a 2" lift then I installed a 4" lift. I didn't get vibrations till I changed gear ratio's to 4:88 then I started getting a slight rythmetic vibration at 75 MPH. It was vibration free till then. Your SYE should with the cv joint should overcome your offset with no issues. I am guessing you have something going on with your rims or tires.
I will tell you this as an opinion. I went to Moab and bent the my front drive line on a trail. It vibrated a bit at all speeds. I replaced the front drive line and then the rythmetic vibration came back or was noticeable at 75.
Based on that, I would think that if your offset was the issue it would vibrate at all speeds. Most of the time when you have a 65 mph it is something to do with the wheels and/or tires. I am not saying that is all of the time, and I am not even saying that is your issue, but most generally. If you can swap with a buddy with a known good set of wheels and tires, that might be a free test to see if that is the case, or at least rule that out.