You can always give the dragon a bunch of low level items in his horde and just assume the players will sell/disenchant them. If you do that you should probably just consider them treasure and only count them as 20% of the value of the items. Your players might even find it handy to have a source of residuum in the middle of the adventure like that.
I kind of like the parcel system, but I could see it being a little wierd if you never deviate from it at all. It would get a little silly if your players know that a 3rd level item must be coming up really soon because they have already found a lvl 2,4 and 5 item as loot. So in my opinion at least it's probably better to view the parcels as guidelines instead of hard rules and shake things up a bit.
I kind of like the parcel system, but I could see it being a little wierd if you never deviate from it at all. It would get a little silly if your players know that a 3rd level item must be coming up really soon because they have already found a lvl 2,4 and 5 item as loot. So in my opinion at least it's probably better to view the parcels as guidelines instead of hard rules and shake things up a bit.