Congrats and welcome to a very elite club, rainbow keepers!!!
Have not read the replies yet, we'll see how well I track with them 


IMO you should bring the hatchling up through various sized enclosures. Neonates thrive with VERY high humiditry and that is simply hard to maintain in a larger cage.
I start with a small shoebox size hatchling rack, That seems to work fine for 6 - 9 months, even a year on some. Then move up to a larger sweaterbox size. By the one year mark high humidity is not as crucial but still good for them. That larger tub will easily last to a yearling or 1.5 years old. At that time I move into something close to adult size. My adult size cages are relatively small at 2 foot square by 18 inches tall. But with the moss box and water bowl on top of that there lots of climbing opportunities and they seem to do just fine.
I'm sure most would agree a 3 x 2 boaphole would be fine for an adult. The "2" high would be a better display cage but not vnecessary as the rainbow will ide most of the time anyways.
IMO THERMOSTAT always!! Much better ption than a thermostat BUT be careful of probe placement. I like to put the probe directly on the heat source and OUTSIDE the enclosure. Then dial in the thermostat setting to get the heat you want in the cage.
Get a digital temp gun, I consider this to be one of my primary "tools" for keeping my snakes. In cage gauges are nice biut only measure where they are placed. The temp gun can be used to measure anywhere!!!!
Red lights are bad, tend to dry out the cage!!!! UTH's are recommended. I've also started using RHP's and have no complaints!!
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Thanks,
Dave Colling

www.rainbows-r-us-reptiles.com
0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)
LOL, to many snakes to list, last count:
21.29 BRB
19.19 BCI
And those are only the breeders 
lots.lots.lots feeder mice and rats 

