Is a tinderbox suitable for a customized local package tree?

[Mike Harding]

I'm interested in having a local depository of FreeBSD ports, slightly
modified from stock (PostgreSQL 8.1.4 used instead of 7.4 whatever,
pcre-utf8 so KDE and gnome can be installed at the same time, etc).  I
would be doing this to save time deploying and updating desktop boxes.
I've   Would a tinderbox be good for this?  Any hints?  I tried using
portupgrade to do this but it fails spectacularly at times.  Also, I
want to shield local users from when the package tree is broken, which
sometimes happens for a week or two...

I have already built a tinderbox, I would at the very least need to sync
the package tree -only- after I can verify a build, correct?  Can I just
do a tinderbuild -updateports, or do I need to clear out the packages
occasionally?

Thanks,

Mike H.