why can't I play properly with a group

I just failed another no reload attempt with a "group" (minsc+sorc charname).
i died miserably in the main tent in the bandit camp.
It's a shame because i had some good fun so far.

But in the end i always end up dying in the hardest fights, unless i use the usual solo no reload tactics (=getting immune to everything), which kind of defeats the point of playing with several characters.

Is there any good tip you can share to make a successful group no reload run? or do I have to accept that groups are unsuitable for no-reload gameplay.

Thanks in advance