I am a new 7.5 tonne driver.
When parking in motorway services is it better for a 7.5 tonne truck to park in the Lorry Park area or the Car Park area?
Don’t park in the car park it’s for CARS 
Even at 7.5t you’re a HGV, therefore park in with the wagons. I can see where you’re coming from though, you’re not wanting to take up a space where an arctic might have wanted to park. Sounds like you’ve got some common sense, certainly enough to park sensibly.
No question is ever too stupid. If you’re asking it, someone else is thinking it.
And don’t park so far back that some numpty pressumes it’s an empty space when dark and reverses in to you .