Setting an end date 1 hour later than the

Setting an end date 1 hour later than the

What's the simplest way to have the end date 1 hour after the start date for a calendar view?

I tried adding a variable field and setting it to have an expression of Demo_Date_Time.addHour(1)
which works

but then on the calendar page, I can't set the end time to be that variable (it only shows fields with a date/time property, not variable fields):  http://ge.tt/85F7Jmy/v/0?c