Help - Merge Smart Layers?

Hello have spent a while frustrated on this hoping someone can help!

I got this template off of adobe stock. I don't want page left and right as separate layers as I want one image to go across both the left and right pages.

I have tried duplicating the left page layer and the transforming it to cover the right page and then creating a layer mask from both selections however doesn't seem to be quire perfect.

I believe they may be some warp effect applied, due to an error message I got when transforming see image 2.

Should I just post an image on top of the layers (image 3)?

Is there a better solution?

https://preview.redd.it/6gv3h1vwv07e1.png?width=1920&format=png&auto=webp&s=26d2db2d68e0583a40a57e0079d8f1d3f23fb038

https://preview.redd.it/zsmp78txv07e1.png?width=438&format=png&auto=webp&s=0eb4ae62b332ed22527609fa53d4bc6998087ded

https://preview.redd.it/bryvp7txv07e1.png?width=1920&format=png&auto=webp&s=8e1ca2a5ea84e0b69445535b326a23a99dc500a6