I seriously doubt that it could have been deployed at all on an ACV of the sort from the Vietnam era. Each Lance missile weighs about 3,000 lbs., and including a launch system for it I'd guess it'd be closer to 4,000 lbs. for just a single launcher.
The entire ACV weighed in at about 15,500 lbs. including nearly 1,000 lbs. of armor. Because the armor was deemed marginally effective by the crews and had a seriously detrimental effect on the performance of the craft, it was often removed in part or whole. The armament was normally just 2 x .50 and 2 x .30 machineguns.
Trying to wedge a 20 foot long missile onto a 40 foot long hovercraft doesn't sound like it's going to work either. The picture shown above with two offset to one side is absolutely ludicrous. The missiles look undersized in relationship to the ACV, two with a launcher would likely be more than half the weight of the entire craft, and offset like that it would have a serious effect on stability. Putting a twin launcher on each side would be completely out of the question as this would approach the entire weight of the craft without the launchers.