I do not see any problem with the set up you describe. Just what size of bark are you using? If you are concerned about aeration of the mix I would add an inert as a component to the mix. This could be large sized perlite or pumice or even styrafoam chips (packing chips). Since you did not mention depth of your mix you may want to consider using a coarse grade of charcoal on the bottom blended with a coarse inert with a depth of 1.5 to 2 inches and set into one corner of the tank a "tube" that sits on top of the bottom fill and extends just above the surface of the soil surface-it can be hidden by a piece of bark or the sheet moss. This would provide additional venting. The "tube" could be anything like even a yogurt cup with the bottom cut off.

I would only use sphagnum moss with carnivorous plants since the PH needed is similar with both. It is available in sheets and may be what you have. Other mosses are not suitable and could cause various problems.

Awesome advice.

Yes, I'm using sphagnum moss. I'm using a small size bark... a ready-made mix (bark and moss) from cobraplant.com and it does seem a bit heavy, so I do think I will add some peanuts.

I will replant the Nepenthes with peanuts at the bottom with charcoal. After I planted it, I realized I had forgotten the charcoal. Aaargh!

The idea of a tube for aeration is a stroke of genius!! THANK YOU!!!! THANK YOU!!!!

Sincerely,
jeff