When i've employed people, I tend to be focussed on their ability to get stuff done, and being responsive to requests, especially external users of the system.

When i've employed people, I tend to be focussed on their ability to get stuff done, and being responsive to requests, especially external users of the system. Hours spent at the desk is just a proxy for the above, and there are better ways of measuring it these days, so i'd think that your bosses will be cool with this unless that have a rather different mentality. I've worked with people with very strict working hours who will never respond to an email outside of those hours, and other people who would be late into the office most days, but would respond to a support problem at 11pm at the weekend. We're not all the same, and there is strength in depth.