I know you said you tried the melamine racks but here is a link to a DIY for the ones we use for adult bps and LOVE them. These are 41qt racks that fit even our biggest females, there's enough space in these racks for the female to self regulate her temps (which are a great plus for follicle developement)!

https://www.americanmadeexotics.com/41-quart-rack.html

Hopefully this helps you out a little. ;p