Wireless/remote start of 7-segment clock

I'm building a 7-segment display clock for track & field timing. We're using these from sure-electronics.com http://www.sureelectronics.net/goods.php?id=721 I'm using these in another project and they are fantastic!

My desire is to use a wireless trigger, most likely this one http://www.finishlynx.com/product/accessories/radiolynx-wireless-start/ and interface it to my Arduino board that's driving my 7-segment clock to START the display.

What I then would like is a very small button or wireless device that could be held by a finish line official to STOP the clock; ie, send a signal to the Arduino to STOP the display and show the lead runner's time.

Subsequent plans would be to provide all of the finish line officials with a wireless button and store clock results in memory and cycle through them for each runner. One step at a time though.

Traxxtar:
I'm building a 7-segment display clock for track & field timing. We're using these from sure-electronics.com http://www.sureelectronics.net/goods.php?id=721 I'm using these in another project and they are fantastic!

Are these visible outside in bright sunlight?

What I then would like is a very small button or wireless device that could be held by a finish line official to STOP the clock; ie, send a signal to the Arduino to STOP the display and show the lead runner's time.

Wouldn't you want a light beam (or multiple per lane) or something instead?
Relying on a button might be rather inaccurate, no?

Any of the common wireless solutions (simple 433Mhz wireless; xbee; Nordic 2.4Ghz module) would work and would easily enable you to make a small, inexpensive wireless "stop" button.

I haven't tried them outdoor just yet, soon.

As far as timing accuracy, it won't be as close as a fully automatic timing(FAT) system, but better than completely hand-held stopwatches. It's for a very specific meet format where we have only 2 schools competing and no need for a FAT system. I'm just looking to provide a race clock at the finish. Today we have nothing.

I'll take a look at the items you suggested.

Thanks!