GPS Ski Tracker app for iOS 4.2.1 required please?

Hi there, can anyone let me know of ANY gps ski tracker app that will run on my iPhone 3G, which only has iOS 4.2.1 ? Every single one I've found requires a minimum iOS requirement of 4.3. I finally came across one on this website...

http://iphone.brothersoft.com/ski_run___skisnowboard_gps_tracker-362670.html

which said minimum iOS 4.0, but when I tried to buy and download it, it too said it required a minimum 4.3 OS. I'm completely new to all this and have never had a Smartphone or iPhone, but am finding it really frustrating and time-consuming trying to find even a basic GPS ski tracker app with basic features of speed, distance, altitude, etc. Apple Support UK tell me my phone's OS cannot be upgraded any further, so can someone else please advise what I can do or where I can find a suitable app? Thanks very much in advance for any help.😕