This event will concern me too... as my party consists of six sorcerers. After reading that the pocket plane is destroyed following challenge number five, *conveniently* before the final battle, I feared that resting would be a problem. I guess the only thing we can do is follow Greadius' advice and stock up on scrolls, wands, etc. Also, all the mages/sorcerers should sequence as many spells as possible, using all three of the sequence spells prior to the final rest. And both contingency spells too.
Ugh... the thought of conserving like that just makes me cringe. Oh well, nothing will stop the Rainbow Magi! Not even a lack of spells... ok, maybe that would. Well, you get my point
Good luck!