Hi welcome aboard! Upper/lower is good IMO, some great bodybuilder went this way, you can get great results with that, this is what I'm doing this year myself.

Depending on the intensity you put in your training, if you do all of what you have listed, it can be a lot of volume and eventually might wear you down... you'll see by yourself and you can adjust down if you begin to feel it's too much.

As for tips to help you maintain afterward, try to eat most of your carbs around the workout, the meal before and after. Always try to avoid eating fat and carbs together, keep protein up all day long. For example if you train in the afternoon I would split my food like that:

Breakfast: proteins + fats
Lunch: proteins + carbs
Pre/Intra/post-workout: proteins + carbs
Dinner: proteins + carbs
Evening snack: Proteins + fats

It's always good to keep protein high but fats and carbs should be moderate and you can adjust the amount of carbs/fats you take up or down to find the sweet spot where you keep your fat % stable.

Cheating once a week is ok and help to keep you sane.

Eric