I.love the Rhodes rolls idea! I actually have a bag of them in my freezer. Just curious, do you not have to make hamotzi on them? Does frying them change it to mezonos?
Ask a rav. It's not simple. I once asked this question.
Are you in America? If yes many regular supermarkets have the Rhodes dough or dinner roll dough in the freezer section with a hechsher.
If you need to make from scratch. Make the dough, form into balls and freeze the balls in advance. Defrost fully the day of and fry in a few pots at once. Deep frying is quick.
It might be worth looking into buying some sort of kitchen machine to help you with the dough. To make enough dough for a few hundred doughnuts by hand will be a lot of work! Maybe you can get hold of something cheap? And even resell after you're done with it, if you won't be needing it again?
I also second freezing the uncooked doughnuts! Then at least you don't have to do everything in one day.
The dough freezes very well, I do it every year.
