Lots of places with no roads up in the High Canadian Arctic. Longest distance for a sling load (4 trips with longline) was 650 statute miles for me (round trip). I had the longrange fuel tanks installed and we had to do 1 fuel stop on the way back. 1 trip a day and we never knew if the weather would be still good enough to come back to camp.
Then the next 4 loads were about a little bit more than 520 statute miles, Had a chance to read some good books doing that. Of course the loads were built to fly properly. Lasted for a month, flying and substracting roughly 80 to 100 miles every 4 loads.
JD