Bulbs are the best way to heat garter enclosures period (IMO)
I can verify through personal experience that they seem much happier with an illuminated basking spot vs a rack set up with heat tape, or and aquarium with a UTH. Anyways here's my garter "rack" hope it gives you some ideas
If you look closely you an see "my girls" utilizing the basking platforms I have provided them
This is where I house pairs together except when the females are getting ready to drop, I then move the males onto a traditional snake rack where they appear quite miserable, but it's only temporary then back with their girly freinds they go
