AZOI.IS: Actually, that (having boys go out with girls older than themselves) is the easiest suggestion, and the one that involves “freezer manipulation” (only allowing boys out to date girls older than them). Its also the simplest to implement, with the least amount of “adverse effects” or “interactions” (as the boys would not be dating then anyway).
Just like the Rabbonim push Kollel, they can push marrying older girls. As Oomis & others have pointed out, there are stong advantages to a couple looking to live a kollel lifestyle to marry someone who is already been working for a number of years.
PM: Perhaps the boys’ mothers (& themselves) would have a change of heart if there was a full page “Kol Korei” in the Yated, signed by everyone who signs all the bans, how they should have their children go out with older girls. I’m not saying it will always work (a relative of mine went out for 2 years with older girls, only to marry a younger girl who was suggested previously but put on hold), but the attempt should be made, especially if the boy would not be dating during that time either way.
SJS: you point to the “harder to be a good boy than a good girl” argument, which is logical. You have agood point with the fertility. Telling a girl to wait to get married is also unfair.