a 20 gallon tank would hold as much as not filling that 30 gallon tote....its alot easier to cut into the rubbermaids though.. so that gives a + on that end.. plumbing.. u will need a bulkhead for sure found easily online.. if u want a sump/fuge, u will need bigger then 30 gallons if u want it to have the wet/dry filter in there, your heater, skimmer, and a fuge to boot... im cookin up my own concauction..
a 75 gallon tank.. already have a 20 gallon sump with wet/dry.. and i am going to pipe in a separate 15 gallon fuge that is blacked out on the sides and back and has a cover on the front so i can run the lights at night, or 24/7 if i decide to, without interrupting the fish, or causing alot of algae growth in the sump..
so far i have drilled a 1 1/2" hole in the glass of the soon to be fuge (15 gallon tank) but now noone sells bulkheads locally at all! so i have to order them online b4 i can drill into the sump.. silicone wont adhere to pvc very well especially on a rubbermaid that can flex and break a seal! that is why u will want a bulkhead for the hole.. if you would like to see pics of what i got so far, and how it looks, let me know and i will post pics for ya..
id be happy to help u out if noone else can... even if i can only help a little or just give ya a few ideas..
i just wanted to make sure u checked the DIY section first, thats why i said that.. some people just come in and dont know about that section...