Kind of the same twice to three times a day 5 mins each time . Mine are in paddocks so that may explain time difference as I don't walk all the land - also mine choose latrine areas and are pretty consistent in choice.
I'm in pretty much the same situation OP as I have some lush forbidden fruit grazing and they have denuded the rest. If you go for the hay option then soaking not steaming will remove calories as steaming only deals with dust and spores etc.
So sorry OP only you know your horse and his situation and you don't seem that you would make this decision lightly so my heart goes out to you.
Be kind to your lad spoil him rotten and be kind to yourself but also be kind to your OH to .... we live in our dreams every day where we are...
Things are so cheap nowadays it's silly not to replace :) I have an advanced case of "Equichav syndrome" wearing my horse and hound fleece and Ariat clogs when I have no intention of getting on a horse.