the risk of deep space exploration.... that's like suggesting there is risk in trading or mining.
there are many reasons to not like fleet carriers, but impacting risk in this game isn't one of them. Remind me where the risk is again as I've never died doing it and i spent years out there without a fleet carrier and with one, and I've never died space trucking, and considering how much wealth all of these activities bring to even newbies, i think the risk factor is extremely low to none.
we know moving a carrier from one system to the next is no different than a ship if it doesn't have a bunch of stuff tied to it that interacts with the bgs or other players being currently docked. we see that with colonization ships.
so the simplest remedy would seem to be to let players disable the things that make it so hard to move fc's if they don't care about those things. turning them on or off would suffer the delay we currently see for jumping, but once off, we get 3 min jump times and no concern for time slots.
bonus, allow us to choose to make fc's isolated to the owner's instance if we want... they can't be attacked anyway... so we can also get rid of the system slot issue. turning that on or off would require only the owner's stuff to be on the carrier and it would have the delay to acquire a slot as if it was jumping the conventional way.
that should buy the time needed to fix the conventional way, as that design seems somewhat broken.