First of all, your belt is an integral part of your carry system. You should not use a cheap belt. However, a good, stiff gun belt might be worse from what you are describing. I can't really picture what your problem is. I am not familiar with the Level 3 Duty holster. It is a different animal from the Level 2 holsters as far as belt attachments due to the standoff for operation of the hood lever. It doesn't sound like you can even use a Serpa paddle attachment, just various belt loop attachments.
I like the Level 2, especially with their very secure paddle (inside and outside the pants hooks), because the gun rides tight to my body. It looks like this hangs out away from your body quite a bit. I don't like that.
I don't know what pistol you carry, but you might try either a Safariland ALS, or if you like the hood style (it has some advantages), a Safariland SLS holster. Safariland holsters are excellent and are not expensive, especially mail order.