Warrior maps grinding?

Camilla map on hard mode (lvl.35) = 75SP/map (150SP on doubling SP events)

Just keep your units in the beginning area. A healer and two dancers are useful.
If you want to train a dancer, don't forget to unequip their dance skill.

Part 5 on Hard mode is the perfect map to SP grind your units as the enemies hit much less harder than in Lunatic.

For your P!Olivia I'd recommend getting two of your most bulky units and unequip their weapons, this will cause the enemies to target those two and will keep Olivia safe from them if you put each of them in the two gaps where my Lucina is, plus your tanky units won't accidentally destroy them since they won't be able to attack.

If you have H!Sakura, make sure she has Dagger Valor and add her to your team, now your Olivia will be getting 12 SP for every enemy defeated today and tomorrow due to the double SP.

I trained P!Olivia today on that map, fairly easy.

Removed the dance skill ofc. Then added three other dancers
* PShigure
* Olivia
* Axura

PShigure tanks on the left all of the red units (could work with Azura, Ninian or any tank). POlivia kills everything from the distance (everyone but Camilla dies in one round, usually two hits. I've given her Luna).

Then Olivia, Shigure and SOMETIMES axura dances to her.
When P!Olivia hits the reds, she heals P!Shigure that can survive longer :)

I have enough with three dancers and no healer.
If need be, one of the dancers can heal a bit (POlivia, PShigure).