I use hot glue, but Shane Speak shows a YouTube video on how to build a simple cigar box preamp that would do the trick. I just did it for the first time and it sounds awesome
I use a beer bottle tops hot glue the piezo in it then gule the cap to the under side of your through neck I fine it works well and not so bright and loud as on underside of top .there's a you tube video that shows you how .
I put a mound of hot glue on the neck, inside the box where the bridge will mount, apply the piezo, then a mound of hot glue on the piezo, and close the box. I leave no space between box lid, glue, piezo, glue, and neck piece, but try to make it so the rest of the neck doesn't touch the box lid. I get NO feed back at all, and it's plenty loud.
I am irritated by the "surface" noises of touching the box lid and having the piezo magnify it. Hot glued inside a bottle cap and to the lid is waay too sensitive, so got some 1/4" cork and put that between the piezo and the lid, much better. However, I am thinking of trying your neck mount method as an even better solution!
Try under the through neck not on the lid I found that way is the best for piezo in the bottle cap les noise from the lid .