I just got a new Icom 703+ and purchased a 18aH 12V SLA battery for it. I use a Par EndFedz 10/20/40m dipole thrown up into a tree and can talk to anyone worldwide. Now, this doesn't cover local 2m/70cm frequencies, but it's a great setup to take backpacking which doesn't weigh too much. I use the bigger battery because I want as much operating power at that 10W I can get. You can downsize to a smaller 7-10aH battery to cut weight. But keep in mind you may also cut your transmit power too. The Yaesu FT-817 is also a fine choice and in my opinion smaller and lighter than the 703, but you can only do around 5w out max. It comes with a battery back built in though.