It's probably the easiest to go 5x Boomkin, unless you need tanking and/or stronger heals.
Instances the 3 boomkin, 1 resto, and 1 feral route is probably the best.



If you have a dedicated healer and want them to assist with the dps, different macro's can help.
Put your default spam dps on say key 1 for everyone other then the healer.
Put the same macro on key 2 for everyone, including the healer.

When you'll need heals, spam 1 so the healer is not casting.
When you won't need heals, spam 2 so everyone is dps'ing.

Alternatively, you could go with a series of keymaps for the healer.
We already have an FTL key, for when we press 1, it determines target and then sends 1 to each client.
Create a group, which does not include the healer.
Change the target of the default FTL key, to this group.
So when you spam 1, everyone except the healer also spams 1 and FTL assists correctly.
Then create another FTL key, triggered by 1, which sends FTL assist and the 1 key to the healer only.
And make a toggle key, ideally two steps. Step 1 enables the healers FTL 1 assist key and step 2 disables it.
If you're playing multiple groups, you'll want the 1 FTL key to still work for them too, so be aware of that if you alter it.