Hi Clint,
I did not see your question until now and am sorry about that.
I have been keeping a very lightly loaded propagation tank without a skimmer for some time now and while it does support the corals and one fish it does require a good amount of work as far as diligent water changes.
The live rock works great as a biological filter but it does not work well in the removal of nutrients that build up in the tank. Without other forms of removal, such as skimming, we must use other means of removal or water changes, which are one of the easiest for me.
Deep sand beds are very efficient at removing various forms of nutrients, such as nitrate, but it does not remove all nutrients, which contribute to algae outbreaks, or other problems, which is where water changes would be helpful in many cases.
I would also suggest using various forms of macro algae to remove nutrients when a skimmer is not being used. The algae uses nutrients as food and when you prune the algae the nutrients are removed with it. A good refugium or algae filter will remove nutrients when skimming is not employed.
It is very possible to have a successful tank without a skimmer as long as you employ other means of nutrient removal in amounts needed to remove nutrients created by the stocking levels.
Doug