Splitting path into segments of 200 points

Offhand, I don't know of anything to help with this. However, depending on the topology of the trail segments, you might try the following. When you import a track into the Explore web site as a route (as opposed to importing it as a track), it will automatically "thin" the points for you. The result may or may not be suitable for actual use. For example, if the segment covers a lot switchbacks (and you need to follow them), this isn't going to work. On the other hand, if the segment fairly straight, or has only a few sharp turns, this will work fine. So what you might try is to manually separate the the file into manageable segments, then import each as a route and see what you get.

Depending on the specific iR unit, you might also be able to make use of the raw track rather than turning it into a route. For example, the 66i is capable of following a track on the unit itself. It is also capable of displaying the track on the map where you can follow it graphically. On the other hand, the Mini cannot follow anything other than a route - and has no map display at all.