I am late to this discussion, but I wondered if I should consider getting a dehydrator. I currently use a food heat lamp and fan combination. This results in a very smooth, slightly shiny surface and does NOT dry out the cookie. The drawback is that I can't put very many cookies under the lamps, so it slows me down. I always felt that a dehydrator must dry the cookie so that has been my hesitation.
If you don't leave them in the dehydrator very long - just long enough to set the outer layer of icing - the result is basically the same as what you described.