This is what I read as well. I think the OP was going to use a 10gal as the baby cage and upgrade to the adult size. OP, please clarify!
** I know you are wanting the largest snake possible for this size enclosure, but please keep in mind that large snakes need large cages. As long as you are realistic and recognize that this type of enclosure will not house ANY "large" snake, you'll have some decent options.
Personally, I would NEVER put a BCI of any type, Hog Island or any other, in a 36" long enclosure for it's adult life. BCIs need room and a minimum enclosure for them would be a 48 x 24 x 18. And that is the minimum for the smallest localities and sub-species.
However, there are several snakes that would do well in a 36 x 24 x 13. Rosy and Sand boas were mentioned and these guys are great choices. I am not familiar with Spotted or Childrens pythons but I do know they stay quite small. Certain colubrids like garter snakes or the smaller locality milk snakes would do well.
If you have room to go taller but keep the same width x length footprint, you can go with a Green Tree Python or a Jungle or Irian Jaya Carpet Python. You'd only have to go to 24" high which isn't much. I keep my large adult male GTP in a 36 x 24 x 24 and he is a very happy camper.![]()