Blimey, early to rise and early to bed, I'm hardly likely to change now after sixty odd years. We are usually on the 'ramble' by 08:30, fours hours walk and break for lunch. Under your system I would be kicking my heels for four and a half hours before we could set off then require lunch after only two hours. By the time we got home it would be almost bed time. If it ain't broke don't fix it.
Why don't you eat lunch after 4 hours of walking?