Question about hot spot for gravid females

Well, I am pretty confident that my female Poss Het Pied is Gravid, I can see 3 lumps, that are kinda squushy when she slides through my hand to go back into her tub. My question is what is the ideal temp for her hot spot? I have her in a rack in a 42 quart tub, with 4 inch strip of flexwatt hooked up to a thermostat. I had the temp set to 90 degrees, but a friend of mine say I should set it to 88 degrees for her hot spot. So which is better, or are either fine?

I prefer 88 as long as she already ovulated. too hot for a female that hasn't ovulated can cause a premature ovulation = slugs.

I put them all at the same temp I set my incubator at. You don't want it too hot, and of course you don't want it to be too cold either.