Others may disagree with me, but I don’t think dogs have the same concept of time as humans do. If I put my dogs in their crates for an hour or for three hours they behave the same. I just make sure they relieve themselves before they go in and straight outside when they come out of them.
It does depend on the dog too. I feel I could trust my 6 month old puppy with free run of the kitchen (with crate door open) but not so his 15 month old sister.
During the night they are crated from 11 to 7 which is a considerable time, but that is their routine. In fact, last thing at night they race into the house as quickly as possible to settle into their crates and get their bed time biscuit.
Good luck with finding a good dog walker. I have never used one but I have seen a lot who are completely irresponsible and just seem to take as many dogs as possible, Remember too, that your puppy will not be needing the same amount of exercise as an adult dog and if the dog walker takes multiple dogs together, your pup may be over exercised. At 17 weeks your little one should only be having 20 to 25 minute walks.
Dogs do adapt and while it isn’t ideal to leave him for 4/5 hours while you are at work, sometimes it has to be done. When I had my two previous cockers, I always tried to work just half days (but even that meant with travel time about 4 to 5 hours ) but sometimes for financial necessity I had to do the occasional full day. I used to worry all the time about the dogs being in their crates all day and would rush home to let them out feeling really guilty but the dogs were always fine. Personally I would rather my young dogs be crated and safe than free to roam the house and thus endanger themselves. You will know your own dog. My two previous cockers were about 2 before they had free run of the house. My GSP at 7 years old was never allowed free run as he was a totally different character