use a couple larger totes... the ones that sell for about $15 at walmart
bottom one could be a water reservoir with pump/pumps pvc, and sprayers etc etc...
top one could house your plants with all equipment housed in there comfortably(would still house hps ballast outside) then vent out hot air from light...
copy and scale up something like
this... except instead of foil or mylar I'd buy elastomeric paint and cover the inside with it or cover cardboard with it and line that around the inside.
add a diy activated carbon filter, hps lighting, cooltube and inline duct fan then you have a nice setup... stack other things on top of it to make it looks as though it belongs and is acting as storage or in my case the table for my printer.
use a supplement called bushmaster in last 4 days of vegetation around 2 feet SPARINGLY and it will stop your plants from going over 3 feet guaranteed and will instead grow outwards and bushy(this is a great thing).
as far as cooling another possibility would be to have part of the bottom tub top cut out to act as a ventilation with a fan there(be sure not to let light into reservoir) and to have the water filled with ice... this could cause some possible PH problems as it is dissolved but would be worth trying.
-potlike