I use rfd900 modems with good results.
Sometimes need to fly in mountains and hill zones, and frequently loss link due LOS issues.
Is there a relative low cost solution for a Satellite link? i mean for low bandwidth telemetry, no video
Here is the solution http://www.rock7mobile.com/products-rockblock-9603
We only need Tridge to implement the " lightweight " mavlink, were we can select only specific messages to be sent/received at long intervals, and only when the main telemetry link is down.