Appointments+ HT Allow hour long appointments to start on the half hour

Going bananas...
I have two services,
1) Personal Training 1/2 hr
2) Personal Training Full Hour

If I choose 1/2 hour, I see all the nice 1/2 hour times like 9:30 and 10:30 etc. But if I choose Full hour I only see 8,9,10 etc. Now, this would be fine except I occasionally want an hour appointment to be able to start on the half hour! Most of our classes start on the half hour so I need training to start on the hours in between.

I feel certain this can be accomplished... just need a little steering.