I travelled on Explorer in the past and am leaving on Sat. ( april 19, 2003) on the Grandeur.
One of the ladies in our cabin brought a mixer that worked off betteries, very lite weight and very convenient. We all brought sports bottles and we were able to mix our own drinks. You can pack the mixes and they will not be confiscated since they do not contain alcohol. Be aware that they will probably check your carry on more closely for alcohol. We also used these bottles to put ice tea, water with lemon, etc. at no cost. We also brought "shooter tubes" which can be purchased at Sams and can be used to make drinks. 5 per 4 drinks.
These are easy to pack.
Also, at breakfast, we got extra dry cerealin the individual boxes and used these when we went snorkeling and for snacks. You can also used these as trades for shopping on the private island such a Labadee since these are hard to come by for the natives.
just some information.
have a great trip.