I've dabbled a bit with that command section thing, since some OOBs I have modded really called for it.
IMHO the best solution to circumvent the problem of command sections being too light and fragile is to reinforce them with as many men and support weapons as possible.
In some cases (French OOB pre-90s) the official OOB puts most heavy weapons in the command group. ON the other hand, f.e. the Austrian OOB called for a 4-men command section with only rifles and grenades. The J�ger platoon is so full with support weapons that it doesn't fit the 10-unit limit anyway, so I have gone for a dedicated command+AT+sniper 9-men section, which ends up with more manpower and weapons than a regular section. In lighter platoons (less manpower and support weapons) I have used a scout class for the command section as some modders have suggested, since that's what the command section actually stands for.
Rather than light separate command elements, what I had in mind for the US units was more in the line of a dedicated infantry section (full manpower) including the platoon commander, so basically similar to the baseline section.
Think of the Soviet motor rifle platoon: three 7-men squads plus one separate commander. The 2nd lt takes command of the first squad which gets a bonus in radio rating and support weapons (say RPG-29 instead of RPG-26, PK instead of RPK). So you can effectively identify the command section (provided you know the enemy OOB well enough to be sure it isn't a weapons section) but you'll have a harder time taking it out in priority on equal terms.
That would imply standing by the old way of separating the commanding cadre into all of the sections. That one section which goes into unit slot 1 would get higher vision, maybe heavier weapons in some cases? I'd bet that event he USMC has enough bucks to get tactical radios to all of its squads by now
so that should not be a difference like in some armies.