But if you attach att the feed together won't that trigger all the light to come on? For example I unlock doors the lights come on but so would the reverse light?

Ok so two way switch should have two channels to one.

Earth your led strip,

Connect your led positive to the output on the switch.

Obtain an ignition positive feed,

Connect it to option 1 on the switch.

Obtain a footwell positive feed,

Connect it to option 2 on the switch.

Next the relay,

On the Genlabs DRLR1

Cut the main positive feed leading to the LEDs and run it through the relay unit,

Splice the reverse positive with the relays sensor feed,

The result will be the relay cuts the power feeding from the switch while reverse is active thus preventing blowing of fuses from dual sources.

Next will need to figure a way of bridging power from reverse feed to the strips while the "auto off" relay protects the switch supply's from getting fried.

Fitting another reverse positive feed to the led loom further down stream towards from the relay towards the strip may work or blow the relay.

One or the other.

This is the item I'm planning on using. 290664755380.

It's looks like it has 2 positive cables, so one feed from foot well lights and one feed to reverse. And a switched feed from a positive to turn it on for show.

Looks like it should work nicely!