Worn bushes will generally show themselves by clunking when the steering is turned and car is stationary, although why worn bushes would show at 110mph is beyond me and vey unlikely, more likely to show when braking or at a slower speed
taking the car out of gear at speed would not create any problems whatsoever providing you're on a private road with no one up your chuff
i did say earlier about the tyres, eggs, uneven tyre wear, my bro had a similar problem with toyos, which were replaced as they were a "bad" batch ??
it doesnt shake at all at lower speeds 60-70 mph ? poor balance normally reveals itself in increments