His load out depends on his function. A Cpl in a rifle squad at that point in time was an assistant squad leader, later in the war there was a bump in ranks and squad leaders became S/Sgts and assistant squad leaders were mostly buck Sgts. But for your CPL just out fit him like any other US infantryman. Cartridge belt with canteen and first aid pouch, one or two bandoliers of ammo, bayonet, haversack with a meat can pouch and a shovel, T handle or folding. A privately purchased belt knife was common. A couple of grenades. M1 Garand rifle, no pistol. Pistols were reserved for weapons teams and in some cases out right replaced with the M1 Carbine. Guys might scrounge up a pistol and it depended on what their officers were like if they were authorized to carry them or not. Remember this, a pistol openly worn could ID you as an officer and make you a good target for snipers. Pack systems were not as efficient at load bearing as todays systems are. Soldier tried to travel with the bare minimum. So consider what your soldier is doing, is he up on the line already or is he moving on to another position. Is he on patrol. etc. Try some Google image searches, try ww2 US infantry. You'll get tons of photos.
Tim