@s&s The outhauls are to carry the outboard
pole ends out to the clew of the sail and are made off to a cleat on the inboard end of the pole and so are normally fixed as you say. This is to overcome the problem that the clews of the rolled up twizzle jibs are well above head
height (depending on the size of boat) and trying to clip the end of the pole into the bowline of the sheet on a plunging foredeck in mid ocean is well nigh impossible and dangerous. With an outhaul
you can sit by the mast in comfort, using both hands, and run the pole ends out to the clews. Also, if you had the luxury of the poles being longer than required you could ease the outhaul
and let the clew set inboard from the pole end for a better sail shape.
I don't know if is just me, but the bows of a boat changing sails in the ocean is not
the place to linger. haha
My apologies again - I should have said a rope strop (or just a short length of rope) secured to the toe rail or whatever. We actually used a short length of chain. The downhaul block would be a swivel block ideally shackled to another block running on the rope strop for minimum chafe. However, a forged D shackle, with the D round the rope, would do.
Could you attach the downhaul block to your windlass
maybe or on another rope strop from windlass to stem fitting? Difficult to advise without seeing your foredeck
Ref. the rope crucifix. So long as you end up with four eyes the construction is not critical. There is a knot
called the jury rig knot
(which could go on the end of a spar to take shrouds to hold it up) which is a bit of overkill for this job but it would do.
Whipping rope ends, splicing three strand rope, serving and other rope work is very satisfying and a good way to pass the time on watch.
Size of jibs? Well if they are on a furling gear
then the bigger the better. Often, the length of pole you can easily stow on board is the deciding factor due to the width and curvature of your side decks.
If you are heading for the Trades then they blow on average 15 knots so maybe try your boat out locally in that sort of breeze with a jib poled out and another set flying and sheeted to the end of your main boom with the main stowed. It will give you an idea before spending a lot of money
If you are ketch
or yawl rigged then a mizzen stays'l pulls well on a broad reach with the twizzle set. We set it when we could in daylight but stowed it for the night watch and peace of mind.