I don't know specifically what brand/model cameras you're thinking of taking, but I would start by looking at car chargers offered by the manufacturer first.
All the wall chargers that you've listed do is to drop household AC down to a low voltage (4.3 & 8.4 by your previous post) & also rectify it to DC. Your bike already puts out DC & the voltage is also higher than either device requires, so simple circuitry can deliver the right voltages.
Using an inverter seems like a very round about way to recharge your stuff. The inverter would step up your moto power to 120V & convert it to AC. Then your chargers would switch it back to DC & step it down to a lower voltage than the bike. I know it seems plug & play but I'm sure there's a more efficient way.
Depending on the plugs your devices have, there are probably aftermarket auto chargers out there that would work off the shelf.
This would also be a simple build for an electronics guy (I only dabble once in a while).
If I were faced with this problem, I suppose I would look for the proper auto charger first. Failing that, I'd buy some generic chargers of the right output & splice on the right connectors to hook up to the stuff I wanted to recharge.
If that didn't work, I might brush up on voltage dividers & just build one.