TMAs are just RX amplifiers, probably made of aluminum with cavity filters milled into it. The actual amplifier boards are tiny, the rest is all like a diplexer, splits off the RX band from the TX, lets the TX pass to the antenna and then amps up the RX sends it back.
I would say no, TMA's are not modifiable for anything.
What freq range are the antennas? Some of the 800mhz antennas might be wide banded enough to cover 33cm ham (902-928mhz). Tuning would be out the question, as those antennas are made up of dozens of elements, for bandwidth and radiation pattern.
Find someone who can run sweep gear and see how they perform on 33cm.
Other than that I cant think of any ham or otherwise useful freq that even come close to what carriers run their cellular on.
33lbs of scrap. Your company lets you guys scrap stuff? I could loose my job for turning in aluminum cans, so I hire crackheads to do it for me.
BTW, you climb?