Hey Mark,
Thanks for getting in touch!
That’s a great question. I actually had to play around with the ticket settings a bit to check for sure, but I am afraid that assigning a specific ticket range is not a supported feature.
You can indeed set a SKU when creating paid tickets using Event Tickets Plus, but that does not affect the ticket number that is assigned.
That said, there is a ticket number assigned to each ticket that is purchased and it is assigned to the attendee who is registered for the event. That number is unique and sequential. Here’s a screenshot where you can see two tickets purchased for the event and how one is HM-1 and the next is HM2:

Does this help answer your question? Please let me know. 🙂
Cheers!
Geoff