Wow!! A road trip to NERD!!! Lucky you!!!
As for cage size... all I can say is what I have done. All of my boas went right into the 3x2x1 RBI cages! Yes, even the wee one who I got from Jimi!!
However, and this is a biggie: These cages are dark on all of the sides and on the top and back...so, a glass enclosure might make a huge difference with the security aspect.
And, again, at a year old and another a couple of months older still, they are ready for their 4x2x6 cages Breaking the bank they are~ but these cages will be their forever homes