Push PBW solution through them to clean (it's how I clean mine). If you're really concerned, make sure you have a 'spare' keg that you can push the solution into the keg you're cleaning. Basically, run it through both directions to make sure you get everything out. Personally, I just push PBW solution through under about 15psi when cleaning them. Some of my kegs can have the poppets removed, while others (brand new ones) cannot. The only time I've had anything get clogged in a poppet was when I was transferring from fermenter after dry hopping (loose, whole hops). Since I now dry hop in keg, in a bag (still with whole hops), it's no longer an issue.
So, basically, yes, you're over-reacting on this.