If they lookreally good, they must be getting enough nutrition. So whatever you're doing must be OK.
If it's going to be very hot (like over 90) during the day,I'd bring in the nestbox. Leave momma outside if you think she will be OK. It might be less stressful on herto leave her in her cage. Provide her with a frozen water bottle or put a fan near her to keep the air moving. Bring the nestbox out to her to make her nurse 2-3 times a day. If it cools off at night, I'd leave the babies for the evening.