If I am just going to do a smooth finish of frosting after the crumb coat, should I cut the frosting recipe in half?

Agreed – it's always better to have extra frosting than too little!

I would recommend still making the full batch, but it is truly my nightmare to be working on a cake and run out of frosting!!!! This frosting freezes really great for up to 6 months if you have any leftover!

Wow, that cake is gorgeous. The instructions say to set aside 1/4 of the frosting for decoration, so to be on the safe side, I’d probably cut back the frosting by no more than 1/4.