What's a good belt I can just buckle on quickly. It will be used over clothing, there will be no pants belt underneath and many times no belt loops.
SH,
If I'm understanding your question correctly, I would just purchase a law enforcement style duty belt of your choice. Preferably nylon because it is lighter and won't sag as much without keepers and a waist belt.
They're easy on, easy off, and you'll still look great. Even without pants.
Anything Safariland or Bianchi should be pretty good. But something as simple as Uncle Mikes may serve you well.
Travis