I've got quite a bit of experience with the 817. If you go through the menu and shut down everything that requires power, and run the HF side at 1 watt, you can make the batteries last quite a while. It can be a power hog....but it's a heck of a little radio. Folks who buy them usually won't sell 'em.

Back country antennas I use:
1) 1/2 wave wire against a 1/4 wave counterpoise. I built a tuner from a poly-varicon cap and a hand wound coil with taps, all in an Altoids tin. 24 ga. wire, no coax except between radio and tuner. This is the lightest system I've come up with.
2) Pre-cut, tuned, inverted "V" with RG-174U coax. Light, but a one band antenna. Super easy setup, no tuner needed if you only work one band (which I usually do).
3) kite hoisted long wire. I use another homemade L-C network tuner with 200ft. of 28ga. wire, and a pocket parafoil kite. This one requires a 1 meg ohm bleed resistor to ground or you'll fry the radio from static discharg. It's the most fun of the three antennas I've hiked with.

Didn't mean to hijack this post....get two hams talking and things go downhill from there.LOL