Most bikes can take either a saddle-rail holder or a bottle-cage holder. Both hide the tracker well; they differ in installation, frame compatibility and how much spray the mount sees.
Pros: reuses existing bolts, very discreet behind the cage, easy to move between bikes, no effect on saddle position.
Cons: needs free cage bosses, and on a small frame a second cage may compete for space.
Pros: works on almost any saddle with standard rails, completely hidden under the seat, keeps cage bosses free, and sits high and away from road spray.
Cons: less room on saddles with integrated bags or unusual rail shapes; a dedicated SWAT version exists for compatible Specialized saddles.
If the bottle bosses are taken and the saddle has no usable rail space — common on e-bikes and cargo bikes — a self-adhesive holder on a clean flat surface is the simplest solution.