What about a full size file cabinet or storage cab from a Thrift store...etc?
You know...double doors...24-30" deep...6 ft or so tall...something that can lock...and can sit in a garage or utility room and not be out of place...

I can tell you now that 4 ft tall WON'T be enough with a WF plant! It will grow that tall in 4 weeks in VEG alone...

go 400 switchable or digital on the ballast so you can veg/bloom in place in the same cab. ...get a good inline fan and a charcoal filter... work on ventilation most...keep it cool...trim it to form a canopy or SCROG it...and BAM...you'll grow some fine weed.

seeds...strains... kp has a good rec. or..the best INDICA bagseed you can find. The skunkier it was da better.