When you're debating lifeline &
shroud storage, one thing to consider is, how much vital handhold space are you losing via each method? If you had a bit more
deck space I'd say, without question, to store them on
deck. As they truly do add a fair bit of windage, & weight aloft, even on a good sized vessel.
Brackets which hold them securely, low on the stanchions might be a viable option. And assuming that the brackets are stout, then the poles double as toe rails. Which is one of the perks of having them mounted on deck on bigger boats.
Also, if, heaven forbid, you do lose your rig, having the poles mounted thusly, probably gives you the best odds on not having them go over the side, along with the rig.
FYI, on a
boat that size, it's probable that the 2 poles combined (weight) is on par with that of the spar section of an equal length. And their combined windage is a lot more than that of an equal spar section of the same length.
It's ironic, but a round section (even
rigging wire) is TERRIBLE from a windage (Drag Coefficent) perspective. So the less windage, especially up high, the better.