The night before your trip or picnic, or the morning before you go, slice the focaccia in half horizontally. Spread the bottom half with the cream cheese spread. Cover with spinach leaves, then sliced red onion and bell pepper rings. Top the sandwich with cheese. Place the top half of the focaccia on the cheese and press down gently. Cut the loaf into 8 wedges. Wrap the loaf well with foil and refrigerate until ready to pack.