When using Eternabond over top of something else, remember, it will be sticking to the TOP product and is dependent on the bond between that product and the layer or material below it.
...including any DIRT or debris that might be in your Dicor.
Be sure when applying to remove any air or voids...ALL of them. If you get a wrinkle, cut the Eternabond and overlap it.
There is Eternabond with and without a top layer that is UV protected. I'd use the stuff with the white top layer.
For wider seams, put the first layer to straddle the seam itself, then add a layer with an overlap on either edge. I think about 3/4"-1" worked for us to get a permanent bond without any lifting.
I added a layer like that on a MH on the LEADING edge (wind side) to keep it all good going down the road.
We cleaned the surfaces with cleaner and then acetone. We had aluminum and rubber roofing on that MH.
It really does take some time to do it "right" and get it squished into every nook and cranny, but then that is it. Done. Forever?
Good luck!