The easiest and cheapest path would be the old New York "Key Club" (our answer to the Funk Brothers and Wrecking Crew) trick, from the days before 5-way switches: put on a set of 12's, drop the middle pickup flush with the pickguard, use the middle position on your selector switch for "acoustic" tones, and the neck/bridge for straight electric work; while it doesn't sound like a true acoustic it fills the same sonic space in an arrangement, and can be
very effective in that context (listen to the rhythm work on some of the Four Seasons' singles) - just remember that you'll need to adjust the trussrod, action, and intonation...
Another option that would work if you want to keep your present setup would be the Boss AC-3 Acoustic Simulator pedal; while I've seen mixed reviews, they've generally been from players who expected more than a $150 pedal could give - if you're expecting to sound like you're playing a prewar D-28 forget it - and once again, those who use it in other than a solo context tend to rate it more favorably...
If you're determined to add another guitar to the stable, the ESP TL-Series offers famiiar UST acoustic-electric tone in an electric-guitar size body - since deeper bodies seem to be an issue for you, one of these might be $500+/- well spent; the only caveat is that they can be a little hard to find, so you might have to buy one on approval by mail-order...
Good luck, and welcome to the Forum...
