And one more thing ? if you are satisfied with re result ? just Merge all the layers together ? (as you want actually) I've merged only TAIL.
Man tire of this mouse business ? let's paint create a top Payer a go!
Use soft brush with minimum Flow settings (let's say ? 10% -15 %).
I've used Blur on the background of the
I've copied the Key layer. + I've set the opacity at about 80 -90 % - and erased some parts of it.
An there we have it ? Magic some kind of trail is finished) = Crop the file for better composition.
I've used and Adjustment layer ? CURVES.