Long range Arduino communication
There are a numbers of satellite transceivers, as PCB modules (size of a few coins) or boxed-product, that are low power, easy setting up and come with driver library example code. 

Some low-speed equipment is not especially expensive, however, there are data volume charge which may be acceptable if you only send small data once every day. 

Two types, those use LEO (Iridium and similar) does not demand very open sky view as sat is high elevation angles. Those use geo stationary sat (Inmarsat and similar) need open sky toward 'generally south', depending on Latitude. 

These sat have high, medium and low speed units. Low speed, non-voice units are what you need in terms of cost, easy setting up, low power etc.

SBD Short Burst Data Satellite module

Another similar unit from another brand and service provider

For the ham path, you can use PSK31 HF modem which allows low speed (31 bauds) transmission with small antenna and easy setup than traditional HF modems of higher speed (few kilo BPS). Wiki on PSK31

Ham band need 

a) knowledge to choose different freq depending on day, night, seasons, latitudes and solar cycle 

b) depends on countries, may not be full legal for machine-to-machine communication not carrying 'ham traffic' (some country defined as self-training activities)  

OR, can get a commercial license and use HF band (not sure how hard it is) and same ham equipment  

OR use the HF network (fee based or not, 100% sure) for file and email for small yacht at sea. Check SailMail or similar