I've been expecting Disney to sell lanyard fobs or other RFID devices as an alternative to MagicBands, from the very beginning. I'm actually a little surprised that we haven't seen them as yet. I'd expect that besides the lanyard fobs, Disney might also market cell phone cases with the RFID hardware built in, or at least cases with attachment points, and the hardware would come in a separate package, so you could buy multiple cases and move the chip from case to case whenever you want your phone to wear a different suit.
There are a number of YouTube videos showing people cutting into MagicBands. Watching them carefully should give you enough information to make an attempt to take one apart without doing damage to the components. The antennae definitely run down the band on both sides; they appear to be forked, so they run on either side of the holes, all the way to the end of the colored portion of TPU.
I don't know what effect it would have on the whole device to cut off the long range antennae, or even to shorten them. Electronics tend to not like it when you remove parts, so I'd make an effort to keep it all together, even if you think you won't need the long range parts.
I think it's entirely possible to take one apart and mount the device into some other casing. At the same time, you could also make the battery replaceable; one of the minor drawbacks to the sealed MagicBand design is that the battery has a limited lifespan (estimated about two years). But the TPU seems to be injection-molded around the components, they're in there pretty tight and it's easy to damage them during disassembly. It may take you several tries to get one apart intact, and at $13 a pop, it could become an expensive project.
Frankly, given the size of the interior components, I can't imagine doing anything with them other than mounting in a credit-card-size fob of some kind that could be worn around the neck or hung from the belt.
Make sure you seal it up really well, too. Florida is a wet place and water is not a friend of electronics, not even low-voltage stuff like MagicBands.
FYI: Disney managers at the resorts have Mickey-shaped fobs on their neck lanyards with the short-range RFID gear in them; I've seen managers open resort rooms with these. I don't know if the housekeeping staff has them, but they appear to be some kind of passkey.