Hi Calvice !

Yes it's a custom piece, cut a old piece to make flaps is not very easy, and attach flaps not very simple, i think it's Mac Gyver way
I prefer only one system with flaps, i suppose that's more simple to attach and more secure. Otherwise i'll have too scared to lose a flap
I'm noobs user with flaps, but if you will to achieve a awesome result, i think you must take the time to make a custom template, it's a necessary step mainly if you want that the system match perfectly your scalp and flaps to temples.
Believe me, for me the best result is achieved with this way.