Markos
I think you might check your numbers ref the viability of 5 pax to 1000nm in this. Piper's own data claims 1200nm at fast cruise 274 kts, so let's say in the real world that's 1000nm at 260kts. With a tanks full payload of about 300kg that's 2 pax, not your 5. And where does the 5th sit anyway - P2 seat? Really? And as flyboymike says, bladder factor is key too. IF you can get 5 pax 1000nm it will likely be at 180kts long range cruise - 5.5 hrs. I reckon 2 hours max with no toilet is realistic for charter. So you've got a 500nm realistic range for charter with this I reckon.
Moving on to costs, it's the old chestnut I'm afraid - plane DOC's can be dwarfed by crew, crew expenses, landing, handling, airspace route charges, flight planning and AOC charges etc, as Dudeness implies. . Add slow speed, (it does matter), a single engine, a prop and fairly cramped cabin and I see this having no impact on charter I'm afraid. It's a nice family/small owner-driver biz aircraft.
Why your interest in it and enthusiasm ref AOC work?