Personally I would recommend the set up we have for Roly - his crate is within a larger 'enclosure' in a corner of our living room - this means he has his actual crate with his bed inside it but has floor space too, outside the crate, for his food and water bowls and room to lie on the wooden floor if he's too hot inside his canvas crate.
We have had the same set up since we got him at 8 weeks old - he loves his den and we have never had destructiveness because he's never had unsupervised access to the sofa etc - he is 14 months now and it still works well for us.
As long as the person visiting at the 4 hour point is giving the pup a walk and some good interaction this should be OK. (Although that is largely down to personal opinion and people differ in this respect). If all that is happening at the 4 hour point is someone letting the pup out for a wee then I would seriously consider paying for a professional dog walker to give more interaction during the day.
Good luck ... and comiserations to the sofa!!!!!!!!!