I know this hotel- When you say ground clearance, you mean is there a steep dropoff on the ramp to get into the parkade, or a sharp angle at the bottom of the ramp? I couldn't say either is a problem, but I would call first.
Worst case scenario is you might have to park in the Library parkade which is very very close to the Westin. There is a short access road that runs E-W on the N side of the Westin, which you take to get to thier parkade. Instead of turning down that road, you make a lazy right and access the Library parkade instead.