i fact, i dont use the minimal or the spinbase. Sometimes,i use gentoo also, bu my gentoo inst is XFCE.
i have in mind that equo command is enclosed in the spinbase and also in the minimal, since the equo is the command for Entropy, the main package manager in sabayon.
in you case, if you dont want fluxbox, you should use the spinbase ISO.
It not have graphical environ. I dont know if it had X or not. Verify.
for an "you manner" Sabayon:
Choose the SpinBase ISO. install it, normally,with the installer.
then check if it has entropy or not (equo s entropy), if command runs, it have entropy.
then: at first, update repos (equo up),after this, upgrade distro (equo u), then , cautionsly and without removing the deps, remove entropy:
# emerge -C --nodeps entropy equo rigo magneto
if you work without the option --nodeps, many things will be removed, since entropy have many dependencies. I have in mind that even portage may be removed.
or simply, mantain entropy but not more use it.
For this, edit the file /etc/entropy/client.conf, and in the line pseudo spmdowgrades, change disable to enable, this is important for compat, the use of Portage in Sabayon (if you will plain mantain the entropy package,s even you no more use entropy)
Now, you can install all the packages that you want,using only portage,example.
emerge -av openbox
after installed all that you want, you can update and upgrade all the system using gentoo standard commands.
in my case, my installations, i use Portage in Gentoo, and i use both installers in sabayon.
ALBERTO FEDERMAN NETO
Favorite Distros: Sabayon, Gentoo, Mageia and OpenSUSE