It's pretty straight forward really; bigger, taller, heavier guys need wider, longer, stronger gear!
Our mate Peter 'Spida' Everitt, triple AFL All - Australian, clocks in at 6'8" and loves Coleman's BigFoot range. Finally he has an airbed his feet fit on as well, a sturdy chair that can comfortably support him with room to spare, a sleeping bag that keeps his whole body warm and a tent with more room than you can poke a stick at.