Sort of. You also need enough room in your sump for a power outage. Return pump stops, tank drains and you better be able to handle that or you're screwed.
And I'm all about saving money, but have you put together a list of everything you'll need to get this tank running and maintained? If you're already stressing about the funds required to do it, everything is more expensive with a large tank. I know your BF is handy but I doubt he's going to build a skimmer, power heads, live rock, water and a ton of other stuff along the way. Take your forecast and then probably double it... just something to keep in mind.