Happy to help. It's true I was thinking you would be driving, but I was also thinking about roof-mounted panels; so being outside isn't going to change the reality of the initial example.
It's a drag doing all the math; but for this phase you can concentrate solely on amps and amp-hours and specifically ignore volts and watts (and losses and inefficiencies) until you get to figuring making everything play together. Why? 30W @ 12V = 2.5 amps, 30W @ 5V = 6 amps; so don't use any panel listed in just volts or watt. It will just be confusing and for now you are just need to figure amp-hours you need to recharge.*
Let's start by noting that 1,000mAh is exactly the same as 1 amp-hour. In a perfect world, an energy source supplying 1 amp for one hour will charge 1 amp-hour, or 1,000mAh, of batteries. An energy source supplying 2 amps for two hours will charge 4 amp-hours, or 4,000mAh, of batteries.
So you have the 4 Sony batteries @ 4,000mAh per, plus 8 AAA batteries @ 1,000mAh per, plus 2 MP3 players @ let's say 500mAh. That's a new total of 16+8+1,000mAh, or 25 amp-hours of juice you want to capture daily.
So, you need to supply to the batteries, on a daily basis, some combination of amps x hours to equal 25Ah, or 25,000mAh (plus inefficiencies and losses TBD).
So, your first example of the PowerFilm cell would need (25,000Ah storage/1350mAh in) = 18.5 hours in perfect sun to charge all your batteries. Solar panels do create power under cloudy conditions, but let's say you have two hours of strong sun and all the other hours together only double that output, you will need more in the neighborhood of a (25,000mAh storage/4 hours to fill it) 6,250mA power source dead minimum. Which is six of the PowerFilm units and that's still really cutting it slim.
So, here what may work … get a second charger for the Sony batteries. Person 1 carries a Sony charger, two batteries, and a 2,000-2,500+mA panel with a 120V* inverter. Person 2 carries the other two batteries in the same setup. Person three carries a third 2,000-2,500+mA panel with a 5V USB output for charging the MP3s and the batteries (if you find a USB charger).
*I'm not sure about running 120V inverters off of small panels without an intermediary battery bank, so please research that. It may not even be feasible. I would see if Sony makes a car-charger for these, it is likely available.
tl;dr: If three of you each carry two of those units on a torso-and-shoulder-mounted platform all day every day and split up the batteries between you it might work.