You can get terminals that extend beyond the battery and you can make the connections below the level of the top of the battery lower than the actual battery posts. They are what I used on my T6 batteries to keep below my seat swivels.
They are absolutely top grade chinesium rubbish, but they will probably work OK for low current.
If you have so many connections coming off each battery terminal that you are considering these, maybe you should tidy up the wiring and use a little fuse box/ distribution box with just a single connection to each terminal?
Thanks all, I like the idea of cobblers. Just a quick question: as the connections are fused anyway, if I go down the route of a little box should the fuses be rated the same as the original fuse?