I am a big proponent of pre-fast meals that are salt-free, high in protein, and include vegetables and noodles. Vegetables and noodles release water slowly as they are digested. "Heavy" protein and fat meals stick to your ribs.
I also see the pre-fast as a pretext for eating a really rich chocolate mousse.
Salt-free, because salt is a diuretic.
Kashered meat is therefore out. I don't do fish since (not in your mother's day, but in in recent years) almost all fish are dipped in a light saline solution before being sent to market. You can't tell whether the fish you are buying has been salted in this way just by looking.
So I make a noodle dish with a red sauce and lots of salt-free white cheese. Friendship makes both cottage and farmer that are widely distributed.
And then I serve a really rich mousse, heavy cream, butter, whole eggs. Yum. Most commercial ice creams have added salt.
I'm curious to hear your solutions. On beyond (I mean before) eggs and ashes.