I fly a lot. I do much of what you said, flying over water mostly, avoiding corners, trying not to cross too fast. One big improvement for me has been the creation of what I call my "travel avatar". He is just a simple biped cat with no AO and very few attachments. Extremely low script count, and few complex textures. It is important to DETACH your AO. Same thing with extraneous HUDs. just turning them off will not reduce your script count at all. I also have an invisible avatar with complexity 1000 and no AO for critical trips.
I have many planes, but these are the ones I like the best for long trips:
McKeenan 757, hands down the best overall for flying all over the world. Very very large however.
THI JU-52 wasser. I love this plane too, but recent changes in simcross behavior (servers slowing you down at crossing) will cause it to lose altitude on crossing. Be careful.
adventure air sky car. This is extremely fun and also crosses well, like the others. It also goes underwater and into space.
Pitts Special (the Japan one available at one of the small shops at tulagi 2000m, not the Dani): this plane can do anything.