I'm looking for an extender/filler for my spice mix I mix up a red pepper and salt blend (along with a few other ingredients) and put it in a coffee grinder to powder it.  

The blend that I have come up with has just the right flavor for my family's taste, but it is too intense.  We use this spice mix to coat deep-fried tater-tots in a pretty fair imitation of the potato ole's from Taco John's.  When coating the tater tots, it takes a certain minimum amount of the spice to get decent coverage.  But, that makes the flavor too strong.

What can I use as a filler or extender to dilute the strength of my spice mix, so I can use enough to get a good distribution of the spices and not have the flavor so strong.  Any suggestions for something flavorless that can be added and blended with the mixture?
The professional (read: industrial) solution would be maltodextrin powder. It is rather tasteless, has good solubility in liquids, and doesn't change much texturewise. 

In homemade spice mixes, the popular filler solution are dried breadcrumbs of a very small size (like breadcrumbs for schnitzel breading). They are noticeable, because the mix gets gritty, but the consensus among those who do it is that this is a feature, not a bug. They could also slightly thicken a wet dish (soup, stew), but present no problem when strewn over dry food. 

You can also use a nut flour made of nuts without much of an own taste, like apricot kernels or low quality overdried almonds. Again, this will be somewhat gritty, but not as hard as the breadcrumn solution.