One-handed reloading of a pistol crossbow?

[ravenfish]

When choosing a ranged weapon for a character with the One Hand disadvantage, I considered the pistol crossbow, which can be fired one-handed but theoretically needs two hands to load. I was wondering if there are any official rules for loading such a weapon one-handed (presumably by taking extra time or requiring some sort of skill roll). I have looked through Low Tech and Martial Arts without finding anything promising, but it is possible I have overlooked something, and I have vague hopes that someone can direct me to a High Tech supplement (with which I am much less familiar) that has equivalent rules for gun loading that could be borrowed. Assume that use of "cinematic" rules is to be minimized if an alternative exists, and that the character does not have any mitigator more advanced than a hook or stump-knife.

[If no one can come up with anything, a house-rule I am considering would be to multiply the time required by a factor of fifteen, as that corresponds to sufficient "extra time" as per Campaigns to cancel out the -4 penalty to success rolls for a task that is difficult but not impossible to perform one-handed, so that pistol crossbow could be loaded in a minute of awkward bracing and pulling. In the absence of official rules, does this seem reasonable to people?]

On a related note, once that crossbow is loaded, is there any guidance (either in terms of GURPS rules or reenactor experience) for how long it can stay in such a state? Obviously it doesn't need to be kept drawn by muscle power like a self-bow would, but I understand that torsion weapons tend to degrade if kept stretched for long periods (certainly, my rubber-band weapons exhibited such behavior when I was a child, and I recall references to needing to unstring bows when they aren't in use). If the character keeps the crossbow loaded under his desk ready to whip out and fire, is that asking for it to fail when it's needed?