further to my previous post, replacing fruits with leafy greens will remove a bunch of calories from your diet. i get the impression that your work is very physical - this reduction in energy input may not be practical, but the metabolic impact could be helpful to stave off the hunger. if you remove these cals and are happy with your weight then make a conscious decision to add them in somewhere else to avoid making them up through snacking on "bad" foods.
also, coffee is an appetite suppressant, but it does other interesting things to metabolism (can contribute to insulin resistance and other funny things, though i doubt that's an issue in this case) and it's a diuretic so i wouldn't be adding it to your diet just for the sake of it. by the same token, i wouldn't be removing it if you only consume it in relatively small quantities.
i crash hard after a lunch of rice or potato - i ride the sugar high for a little while, but i come down hard and am starving and tired by mid afternoon. is there a lower-GI carb source available to you? oatmeal, cous-cous, brown rice, wholemeal bread, wholemeal pasta?
in terms of hanging onto muscle, do you have access to gym equipment? full body compound lifts (squats, deadlifts, military press, etc) are something that basically every human on the planet should be doing to improve their quality of life and general wellbeing. squat big and you'll go back to your bike with bigger quads than you had when you left. this will definitely not help your hunger issues though - appetite will only go up