Heroic actions in GURPS mass combat

What's less fun (and consistent) with the rules as written

In the rules as written, the odds of a character influencing the odds of a battle are set to a flat 5 (on 3d6). The modifiers are:

1. +risk level
2. +1 if one relevant skill is 15+
3. +1 if the character is a force commander
4. +1 if part of a fanatic or impetuous element
5. -1 if part of a support/logistic unit and in presence of fanatics/impetuous friendlies.

This is less fun because there is no sense of scale: same odds for a D-day invasion or for a 10 vs 10 men battle. This is odd, and left people around the table feeling a bit cold about the mass combat rules. 

The crux of the problem for us is that I often encourage people to color key checks with one "supporting check": some action that will positively influence the outcome and may be performed by someone else (or not). The fix below aims to replace the heroic action check for the more commonly used supporting check mechanism.

K38 - A beard in Hell

Dude, where is my butler?

Bain toured the HQ once more in East Gate hall and started to wonder about Thordar. He hadn't seen the dwarf in over a day. He asked around: no one seemed to know where he was, as usual. Bain had a hunch that something could be wrong, and ordered his sub-commanders to find his butler.

A dwarf from the Mithril reported to the viceroy 30 minutes later. According to him, Thordar may have been caught on the wrong side of the cave in. Bain demanded explanations as to why no one informed him of this. The dwarf replied that he just assumed that someone else had reported.

Both accesses to the Marzabuul stairs were now collapsed. The only way to bypass the cave-ins involved a daredeath hike on the cliff walls of the chasm. The viceroy tasked the rangers to find a path there and ordered his son Gror to descend into the 4th deep and scout the North-South highway that was just discovered.