If you want to use what you have, use your phone and a spare USB charger if it can't handle a full day of use (mine can, but I still keep the USB charger just in case). I use both my phone in my pocket for backup navigation/tracking, a map pouch on the front, and a regular cyclecomputer on the handlebars for speed, distance, etc. You could run a HR meter through a regular computer pretty easy.

Agree with others that a HR monitor is rather unnecessary for touring, though. It isn't too hard to just dial it back a bit, if you feel yourself getting winded just kick it down a gear or two.