RF Power Tools sells 3-band and 7-band low-pass filters modules. You can purchase bare boards to stuff yourself or assembled and tested units. You might also consider using their 100W MRF101 amplifier board.
I do not attest to the specs for the products and I am not affiliated in any way with RF Power Tools.
LC filters make sense as they don't dissipate energy.
Hm, that's kind of true (at least theoretically), but guess what: that energy that doesn't reach the antenna still has to go somewhere, and will eventually be converted to heat. In the case of LC filters, that might be in some ohmic resistances in components and traces, or in the amplifier output stage.