Seriously, the most important tool needed in our guild is the ability to prohibit placing specific hold units in a Ops platoon (preferred version) and/or being able to prohibit placing any units in one entire Ops platoon without affecting the ability to place units in other platoons.
The first version is preferred -- especially if it can be preset before phase start. But while it's a bit of a pain in the neck, being able to close a single platoon would make it possible to prevent accidental Ops fills when we're working on a preload.
Obviously some toons are more desirable to have unavailable on the day you're going for max points (I'd rather lose my JKG on that day than my JML) and so singling out specific toons is better. Otherwise we could designate JKG as a hold unit and someone could place it early. Depending on how the platoon fills up later, a GL could end up being the hold unit with the "block entire platoons" system. Not intended. Not preferable, but at least we could still max out our pre-load and save the platoon points for the next day.