Navaid requirement is for night departures - oops!
it's possible to look back and think "I could have done that better",
Humbly agree - benefit of hindsight, etc.
My FO's thoughts were for that an OCTA pass is easier to organise.
I agree with your FO. But use the 15º too. Separates you OCTA, and very likely to give you the unrestricted climb/descent.
And keep up the mental arithmetic! I think the greatest part of the problem is that pilots are not taught/too easily forget the basic nav. Especially when a piece of shiny kit is in the panel.