Hm this would be quite a challenge since you're parked outside. What might be doable is warm water with multiple microfiber towels. After using each clean side of a folded towel, use another. You'll end up with a stack of towels to wash but it's probably the most efficient. Use a generous amount...
I haven't had any issues with iron removers on trim. Just rinse it off after a short while and don't let it bake in the sun.
I'd suggest coating from top to bottom. Are you taking the wheels off? You can do those at any time.
Haven't used uber ceramic so I can't say how beneficial multiple...
It seems like you're on the right track if you're trying to maintain the condition of your car. Decon, rinseless wash, wax, and 303 for the interior and trim sounds like a plan until you're prepared to correct the paint.