Hi Ellis,
The parking facilities on site are reserved for Residents, day delegates, and leisure club members. The hotel will be operating their own security on the gate to prevent access to the event to anyone not registered as one of the above.
With this in mind, your request is a very sensible one, and I will raise this. If this is approved, the main thing to remember will be that parking is done so at the owners own risk, and the convention or hotel are not responsible for damage to your car. Secondly, you will still be required to leave the venue by 2am when the last dance finishes (although I raise this just as a moot point, because you clearly show intention to do this).
I'll bring you an answer soon.
Many thanks!