I am afraid that planning the 25000 hours lifetime for such truck is a bit too risky.
With the second hand trucks you never know what was their past. What is the condition of the engine, the transmission etc.
Linde is truly very robust truck, but rather don't go too far.

For your application (~ 3000 hours a year) and a second hand truck which already has 9000 working hours you can presume about 3 years of reasonably safe work but I wouldn't plan any longer.

15000 to 20000 hours is a really big lifetime anyway.