I have cruised on a ' repositioning cruise' on Princess, from Fort Lauderdale to LA through the Panama Cannal.
I had also had a carribean trip on the same ship the year before.
Firslty princess padded out their usual entertainment schdule with various entertainers and 'highlights' shows with bits of all of the previous shows.
Addtionally there was some customer 'talent' shows such as kids ( they already do this but could upgrade), and an adults one.
Through panama c, they had a guide on the bridge telling us about highlights and how the cannal was constructed and how the water supply is gained, it was very interesting, but is long we were outside the entrance at 7.30am and finnished at 6pm that night.
On Food etc, it took on extra supples at various ports, we actually saw this occur. Additionally it had an unannouced stop at the port near panama city, to fuel up, for 6 hours, someone said the price was good.
Surley supplies and 'waste' can be taken on and off at any 'cruise' quality port. However It is a big problem at a 'tender' port.
Security might be another issue however nowadays, if they take on supplies.