When the box is hidden or obstructed, you can use Flipper with an IR Extender or an IR (infrared) to RF (radio frequency).
There are many IR - RF extenders available like nextgen.us or similar products available at retailers Amazon.com, BestBuy. IR / RF Extenders are used to deliver the IR (infrared) signal to devices located in a cabinet or another room. Some devices use a base station and wireless to deliver content to various rooms, like Xfinity in facilities, and multi-room setups for Dish.
If your cable box / STB has an "IR Extender" or 3.5 mm plug in the back, you may be able to use a simple IR extender like This IR Extender.
IR Extenders has an IR receiver at the end of the wire, then deliver the signal to the box via the wire and the 3.5 mm plug.