I would not if it is tied into a line to a light as there will already be one to cover the light and it will be just a bit more load on that breaker than without the repeater.
What often gets confused is that we think of the breaker being the right size to protect the load from the light alone but what normally happens is that the breaker or fuse is sized to make sure it trips before the WIRE gets too hot to be safe.
They use some wire size that fits what they want to do like a 16 gauge and then they use a fuse to protect the amount of current that wire will safely carry, even though they may only put a light or two and those lights may only use half as much current as the wire and fuse will do safely.
If we look at the breakers in an RV, many of the light circuits are fed by 15 amp breakers as the smallest size and that often is way more capacity than needed. There is a lot of "slack" built into the wire and breaker sizes, so if we are not adding something that draws a lot of power like a motor, etc. we can almost always get by with adding a little to the load. Your repeater is a small item.
The breaker size is meant to be small enough to trip long before the wire overheats but not near close enough to trip unnecessarily.
In my case of adding a fan to the light circuit, I found there was a 15 amp breaker but it only had one small light on that circuit so even adding a fan motor was not getting close to tripping the breaker. If I added a toaster or electric heater, then I might have trouble!
Which brings up a point on doing this work that needs some care.
When working on the wires, try to make sure that you don't touch the power wires to the ground wires in any way as that is what makes a LOT of current flow and the breaker WILL trip, so you have to go hunt for which one to reset.
The real circuit is more like this with the breaker and if things are normal, the current has to run through the light bulb, motor, etc to get back to the ground and that limits the amount of current that can flow.
But you may have heard of getting a "short" in wiring and it blows the fuse?
That name comes from the current taking a "short" route and doesn't go through the item powered and lots more current can flow, so the fuse or breaker stops the flow before the wiring gets hot!
An electrical short is a nickname for a short circuit and they happen if we stick a screwdriver in a box and make a path from positive to ground wires or metal of some sort. The power takes a "shortcut", too much flows and the circuit breaker or fuse stops it!
I did not draw it on any of my drawings but almost the first step off the positive side of the battery it goes to a breaker before going to the wires, switch, or anything else.