I like the idea of one day disposables for hiking. The backup projection that provides is really good.
I'm a 50/50 contacts/glasses guy, but I normally wear glasses when hiking. If I wear contacts, I take my glasses anyways because it's easily possible to lose, tear or damage a contact. If I just take the glasses, then I don't need a case. If I bring contacts then I'm carrying glasses, glasses case, contacts case and contact solution.
With daily disposable contacts (or weekly and bring an extra pair) you wouldn't need back up glasses.
For solution, I use a small travel size bottle obviously, but I use the same one always and just keep refilling it. Squirt solution from a big bottle into a dish, and then vacuum up the amount needed with your smaller bottle.