Assuming you are not going off the beaten path and are following roads and streets on the route, I would guess your pack could stay quite light as it would not be necessary to have all your supplies for the entire trip. Carry a days supply of food and purchase fresh foods daily. That way you will eat better and you will find that your pack can be considerably lighter.
Staying in hotels along the way could lighten your load much more, no need for tent and sleeping bag. If you are going offroad and on trails, you will find that your weight requirements will climb dramatically. Assuming a winter early spring hike, you will be much heavier than a spring or summer hike, based solely upon clothing requirements.