Thats the way I build guitars with the jack in the side - reinforced on the inside and a plate on the outside. Why anyone would put a jack thru a 1/16th inch piece of wood and expect it to hold is beyond me. And leaving it out on a stand with the plug in the jack just invited disaster.

I've actually done a couple of these. First, reinforce the inside - I bent a piece of birch plywood on my hotpipe, drilled a hole and threaded a piece of string (actually string trimmer string)

So, the plywood I tried bending just de-laminated and cracked. I used 3/8" 5 ply finished plywood.

I realize plywood would be much stronger, but is there any reason not to use a solid piece of wood?

I was going to suggest the Les Paul style plate too, it's what I ended up using on my 64 Tennessean, but it has thicker sides and didn't need the added reinforcement, Prior to using the Les Paul Jack plate I had knocked the middle out of a Toonie (Can. two dollar coin) and used the outside ring as a washer. It was an expensive washer.

I have some bigger and older plywood archtops that have had the plain jack installed in the side for 65 years with no problems at all but it generally only takes one good blow to that area.