Where should I train a 40-72-1 in P2P?

I'm currently training at the guards at Falador for about 21k xp/hr, but I don't think that's good enough. I don't have access to Experiments or Yaks, and Rock Crabs are packed. Any suggestions?

Note: I'm doing a 70-99 Strength order for someone.

 

[Sprawl]

I usually train pures at Soul Wars but if you're not botting that would be an ass.

 

[-x.]

There are some really good scripts for flesh crawlers.
Also the hill giant resource dungeon if it has any dungeoneering levels.