using a shift lever as a brake lever?

hello my question is has anyone ever modded out a shift lever to be used as a brake lever. my reason for doing this is that I play bike polo and only have one hand on my bar at all times I ride free wheel with a rear brake I love that fact that I can skid all over the place but some times I wish I had duel braking power. I know all about running both brakes with one lever but i would much rather have a smaller lever that's completely separate from my brake lever hence a shift lever. I also run bmx U brakes so I'm sure I need a lot of leverage. this may be silly please don't make fun. Thanks!

Shift levers are made for the tiny nipples used on the thin inner shift cables. The outer cables are also different to brake cables and can crush with braking forces. There are so many different shift levers around and they are all designed to take light pressure.

You could shorten a brake lever by sawing and rounding off the end with a file and sandpaper. You will find that a 'u' brake needs a lot of force to work and a shorter lever will give less force... even so, a coaster brake will be better off with any kind of brake helping at the front.

We are talking about this for special sporting purposes! Not a good idea for riding on the road though.

Yes. The local laws over here require a separate braking system, so a fixie rider strapped a shifter from an S-A 3-speed to his seat post and hooked it up to a rear brake. Compliant with the letter if not with the intention of the law...

It would help knowing what bar diameter you're using.

Has it ever occured to you that another brake lever would also be entirely separate to your current brake lever? Or are you looking for a brake lever that can be operated by your thumb?

I can see several options:
1) get two brake levers, one short 2-finger version and one regular. Tinker around with putting one inside the other at various different angles(at the same side of the bar), see if you can't find a setup that'll put both within acceptable reach.
2) get an old school top mount friction shifter. Undo the friction adjustment screw and see what it gives you.
3) get a cross/interrupter lever, set it on the very end of the bar with the lever facing inwards. Ditch your grip, run the cable along the bar under some bar tape.
4) get an SRAM gripshift unit, disassemble and remove the detent. Mount on bar, hook up to brake and see how much braking power it gives you.
5) if your bar diameter allows it, try a TT brake handle of the kind that's mounted with an expander in the bar end. Mount as with the cross/interrupter lever.