BXT will not
get you banned in single-player. There has not been a single report where it has and it is a standard tool used by the majority of the community. This is the same case with, for example, HLAE, which is the standard tool used to capture demos; it can get you VAC banned if used online but not anywhere else.
Even if it did, the GoldSrc Package would not be an appropriate alternative because it runs through your Steam account (which is why you need to own the games on Steam beforehand). The main reason it was created was to have an all-in-one package available for beginners and others who wanted the least hassle possible when setting up, not to have a "non-Steam" alternative like NGHL.
Furthermore, despite this seemingly-common paranoia being completely invalid, in this case you can use NGHL
(which is inferior but does not
use your Steam account), download the WON Package
and inject BXT