Hi Adam,
Unfortunately, it's not currently possible to use an arbitrary sysprep.xml file in conjunction with specifying the option to use the virtual machine name in the customization specification wizard in vCenter, you would instead have to use a random name (<ComputerName>*</ComputerName>) or only use the customization options provided via that method. I believe it has already been raised as a feature request, though it can only help to add your voice to it. The feature request form can be found here: https://www.vmware.com/contact/contactus.html?department=prod_request
Mike