I actually use the same macros... but I DO use F4 - I simply don't allow "Alt" in my Macros-

I use
nomodifier
modifier:shift,ctrl
modifier:shift
modifier:ctrl

Since my party is always in the same order, and my UI shows the party horizontally, it is really intuitive to heal. On my tank (my main) I see:
Priest, Warlock, Mage2, Mage1 (I honestly don't know why it chose this order, but it is always this order). So, I simply set F1 to heal the priest, F2 the Warlock, F3 Mage2, F4 Mage1, F5 heals the Tank and F6 heals the Warlocks pet (which is often my offtank). I chose F5 as my tank's heal because it is so easy to find on the keyboard without looking.