raggie,
Here's a thread that may give you a
couple of ideas.
There's a link in that thread to a cool place that sells tiny "neodymium magnets" with no minimum order. If you have enough of those 'too short' 123's it may be worth while to check if they have
a thin enough magnet to make the batt long enough.
Also a drop of solder on the plus pole may do it. I'm no expert, but in that same thread
batterystation mentions soldering buttons on
flat Lithium-ion cells. I'm just wondering
if a drop of solder would work on a 123 --
or be dangerous.
I'd read the whole thread
and PM batterystation before I tried the solder idea.
I'd like to know what works if you do come up with something.