This isn't an answer, but I'm going to go out on a limb and say you probably won't get one. It's an interesting question, but the data is likely not available.

Even for medieval knights, nobles and commanders we often don't know things like birth dates. Many - or most - didn't leave biographical records of any kind, or even dated tombstones (those became common much later). What knowledge we have about most of these have been pieced together from associated sources such as letters, court and inheritance records etc. If you expand you definition of "crusader" to include the thousands of ordinary foot soldiers, retainers and servants who took part, then the task becomes close to impossible. Such people commonly haven't left us any records at all.

As the previous poster said, there's really no way to tell since we don't have those sorts of records. Fighting men would likely have an average age of late 20s to early 30s, since beyond a certain age people aren't really expected to take an active part in combat, but that didn't mean that they didn't go on Crusade or march with an army. The knightly orders you mentioned are a good example of this, since we know that younger members were often stationed in castles or priories in borderlands and hostile areas, where military duties were heavier, while older members (remember, being a Knight Templar meant being one for life) were more likely to be engaged in administration, preaching or fundraising, often back in Europe.