yep!
i had a junky old 15" collecting dust, resting on a junky old 16" floor tom (just sitting up on a shelf at work for ages!), when the dreaded idea took hold: make a junky, unusual, and MUCH lighter 1x15" for my junky, unusual one-man-band, Amish Drum Machine. I traced the inside of the shell on paper, then made 4 curved pieces of hardwood (each one 90 degrees of the inside radius - about 3/4" thick), and glued them to the inside about 1" down from the top. there's only about a 1/8" extra space around the speaker. then i removed the little vent rivet and mounted the 1/4" jack there. lastly, i thought of gluing regular, white grill cloth to the top head (w/a big hole cut out), but settled on punching loads of 1/4" holes, so it also resembles a giant pepper shaker. there's little sonic difference with or without top head.
the red circles you see on the cone are little thin leather patches (to cover rips) - i did say junky - hope to replace it. but the sound is good, both for guitar and my pseudo-bass (boss oc3). it points straight up, of course, but that's not such an issue with low end anyway. all in all, a good tradeoff since i lug all this gear myself.
oh yeah, tried it first with insulation glued to inside bottom head - very stifled. ended up cutting about a 6" hole in it - much better. and unbelievably, no rattles!