Awwww poor Pup being left alone for two days locked up in an apt.
That alone I would think would make him an unhappy camper.
The trial run sounds like good advise and keeping the food at your
house incase it dosen't work out is also great advise. At least you
can open the door slightly and throw it in
if necessary.
I think that dog will be so happy to see you he's going to be your
best friend. Just be careful. I know I would be scared silly and not
so sure I would have offered to be honest.
How about just opening the door and let him come to the door,
leash him and go for the walk without entering into the apt.
Then when you come back go in. Having spent time with him
he'll be comfortable I would think. Feed him, pat him on the
head and leave.
Good luck,