As you said, those gels are gonna eat up a LOT of light. You can find real blacklight light bulbs online for as cheap as $2/each.
None of this is really that new. You haven’t been able to transport li-ion batteries in checked baggage on passenger jets for years, and you can still hand carry them on-board in the cabin with you, as long as they meet the restrictions. The big difference now is it’s a USDOT rule, not just FAA. The notice reads more like li-ion batts can no longer be shipped as cargo shipments(think large quantities from a manufacturer or dealer) aboard passenger aircraft and can only be flown on dedicated cargo aircraft at 30% charge. But again, we haven’t been able to transport our big camera batteries in checked baggage(under the plane/in the cargo hold) for years.
A/B never did away with their HyTron(nickel medal hydride) batteries and now Core has a nickel metal hydride, as well. I waited until after I stopped flying on an almost weekly basis to switch to Li-ion batts from hytron’s(no travel/transport restrictions). I usually ship my gear ahead by ground if I have to fly, but I also have a lot of Core Hypercore Prime 190’s that split into two 95wh halves to meet carry-on travel restrictions and it actually came in handy back in December when there was a shipping snafu.
I believe the 30% charge state is for shipped batteries(air cargo), not carry-on. Also, Anton Bauer and maybe CoreSWX have chargers that will discharge batteries automatically to 30% remaining power.