I've done the route from Seatwaite but not from Wasdale, although stayed there.
I think the major factor of this is your time restraint of 24hrs. From Wasdale is definitely the quickest way. I don't know for definate but I believe from Wasdale is approx 2 hours quicker, it's a more direct route. If you do have a couple of extra hours then I do recommend via the corridor route, good views and if weather turns the route is almost signposted! But probably the same if returning to Wasdale.
I agree as above that getting your driver to pick you up from a different spot isn't a good idea. Worse can scenario you have to head back then he's gone.
Seatwaite parking is free, Wasdale isn't. No phone signal in Wasdale, not even wi-fi at the pub! Probably none at Seatwaite but didn't check.
Good luck with your challenge