The new Ghost Leader & Speed Stringer have captured my imagination. With the various Rob Allen float & float-line products you could put together some surprisingly sophisticated rigs.
If I understand correctly(?) a rig for big pelagic fish might look like this
large float (e.g. 11 litre solid)
breakaway pouch

Break-away pouch.
float line
11 litre solid float
bungee
floatline
gun-mounted break-away rig & steel line release

long railgun
(Although the Tommy Botha float system looks like it might be simpler to use and manage).
Float system for reef fishing:
8/11 litre inflatible float or solid float with diver down flag & lead ballast
speed stringer

Speed stringer & needle.
floatline
Ghost leader with flasher

Ghost leader flasher.
speed needle
short railgun
Just made myself a couple of trial
Ghost Leaders. I don't have any thick
clear mono or crimps but I do have several thicknesses and colours of strimmer line, some whipping cord and superglue! I made a 2.5mm x 12ft/3.6m one and a 1.6mm x 8ft/2.4m Ghost Lead. I had been thinking of shortening my 20m float line (or buying a 10m). So I have cut the 20m into a 12m & an 8m line, spliced new end loops and made a new lightweight winder. So I will have a shortline (8m + 2.4m = 10.4m = 33 ft) and a longer line (12m + 3.6m = 15.6m = 51 ft).