Yes you can keep Boiga and any other colubrid on a recreational license in Queensland, there is no limit on them. The only limited species are potentially lethal elapids (e.g. Pseudechis, Pseudonaja) and a few species considered at risk within Queensland (e.g. green tree python, woma). On the normal recreational license you can not keep any potentially lethal elapids, but you can have a combination of two at risk species (e.g. one woma and one green tree python, two womas). If you wish to keep elapids or more than two at risk species you can upgrade your license to cover these.
Little bit of a diversion there but again back to the main question you can keep as many Boiga as you want.