You could try the bisbigliando technique (which is easier to write than to describe!) wherein you play a two- or three-note chord with each hand alternating very rapidly on the same strings or - if you have them - their enharmonics. For example, if you want to use a C chord, you could play middle C, E, and G with fingers 3-2-1 of your right hand in a strong rippling manner, then immediately after this, do exactly the same thing with your left hand on those same strings, or else B#-E-G if you are using a Celtic harp and have time for a lever-change. Keep repeating this for as long as you like.

Any classical harp tutor will give further details of this technique. Your inventive use of harp accompaniment sounds like a great idea - is there any way we can hear it?