The large aspect ratio of the surveillance UAVs have little to do with their range, it is because surveillance nature of those UAVs are better suited with such a thing. Long aspect ratio have lower induced drag and are better suited at high altitude, this is because induced drag is higher at higher altitudes where these surveillance UAVs spend most of their time. This is basic aerodynamics:
There are other benfits of having low vs high aspect ratio. Check below article for more details:
Some wings are short and stubby, while others are long and skinny. What's up with the difference?
www.boldmethod.com
You are talking as if a large aspect ratio is a requirement for UAVs to have longer ranges. This is devoid of aerodynamic sense.
The issue is you apparently know much about physics in general. There is absolutely nothing that states such UAVs require refuelling. Most of these UAVs fly for many hours without any refuelling. Even small UAVs can travel for 2500km if needed, check ScanEagle.
You can ask the Saudis regarding the potency of these systems.
Moreover, the point regarding how it long it takes to get there is moot. If we consider a pre-programmed UAV, these will be used to target static targets. I don't think something like an oil facility will be going anywhere in that time. Regarding the issue of detection, these low flying UAVs are inherently difficult to detect.