I don't see a response to your question as of yet, so I'll tell you what I've been doing.
I keep my Kenyans in both rubbermaid, and tanks. Some like aspen,and some seemed to prefer sand. I always change an animals habitat if it appears to not be happy or refuses to eat.
My ambient room temperature is kept at 85-87 degrees (we lower it to 85 when we are working, and push it back to 87 when done).
However my heat tape is set to 95-100.
All my adults are housed seperately except durning breeding. My young 6 months and older are housed in smaller rubbermaid on aspen. Until then the clutch is housed in a medium critter container on aspen and then fed seperately in deli cups. Most feed just fine in a deli cup with nothing in it. But, I have 4 that also want aspen in the deli cup before they'll eat. All are fed live red hot pinkie mice. As they grow, if they appear to be hungry still after feeding,I then double that food for a few feedings. If they do OK on that then I move up one size on the food item and go back to single feeding until they again show some growth and seem to be hungry again after feeding. Then it's back to feeding 2 items of the current food size for a few feedings and then move up in size to the next food size... etc etc. maxing out on usually an adult mouse or pinkie rat.
I did though once have a kenyan who defined every trick and totally refused everything. By accident I found it would eat a dwarf pinkie hamster like it was candy.
Hope this helps.