I never did Paineel guards but I did the Qeynos guards in NK from 34-39 so it was only 3 mobs on a 6min timer.
The biggest reason to use dots is to make sure you're dealing >50% damage so your pet isn't taking 50% of the exp so you want to find a sweet spot of dealing enough damage while also managing your own hp/mana.
You can try this with just rooting if your pet isn't able to rip aggro in a fast enough time to let you med or you can forgo one of the dots for meleeing yourself.
I had a fungi/staff so more HP regen than needed so I face tanked but I also used Walking sleep over Tagars to conserve mana, especially if there's any resists. I don't know how much the melee debuff is helping tbh, might not be worth the mana investment. I'd also recommend getting yourself a decent melee weapon such as
Poison Wind Censor or if you can afford it
Granite Face Grinder and then keep yourself Hasted.
For buffs I only ever kept Regen, Str and Haste on myself so long as it's enough to kill the mobs then I'm not kneecapped with suddenly needing to spend a chunk of mana on rebuffs to throw off my cycle.
Again it all comes down to how much mana/hp you need to kill the mobs and then recover before respawns so throw in DD's if you've got mana to spare. Don't hold back on Canni'ing during combat, I kept myself at 80% hp just to be sure I was never full hp if I needed to focus elsewhere for a min.