You don't even need extra hardware for the duplexing; the common SX1276 chip has separate Tx and Rx pins which are typically combined on the PCB. All you need is to route a PCB that brings 'em out separately, if that's what you want to do.
In practice it's tricky to aim two dishes the exact same place, so using a single dish with a single antenna at its focus is probably quite a bit more practical. The SX1276 also has a PA control pin, invert that and you've got your LNA control signal. Or don't bother with the LNA, and simply mount the transceiver at the focus to minimize RF feedline losses. You'd give up a smidgen of performance but gain a lot of simplicity. (There would still be coax running down the boom, but it would be carrying the wifi/bluetooth signal outside the dish's aperture!)