I rent and grow in a 4x4x7 also. What I did was put up blinds hanging around my tent and moved a bunch of junk around it (see my grow journal and shit if you wanna see) and tell everyone it's a closet because my apartment doesn't have much space.
What you need to do when you rent is tell them a story from my past that you can use and pretend it was you. For you it's a lie but it will save your ass.
You tell them you(which is really me) had a land lord once that used to break in your apartment and steal your food beer and money. Tell them he kept telling you that you couldn't change the locks because the fire department needed to get in and he was the only one with a key(he really said that shit). One day me and my girlfriend put $20 on the coffee table and went to work. When we returned it was gone along with what we planned on cooking for dinner. (no lie)..
This way you can say "I just need to change the locks, sorry I trust you but I've had too many problems in the past I hope it's not going to be a problem"... <--Tell them this before you sign a lease or agreement or exchange ANY money. If they have a problem say "You're welcome to stop in or whatever if you need to but I don't feel safe when others have the key. The last renters could have copied the key and I don't want robbed or raped...etc (at this point wave your money at them and say nothing)" I'm 100% sure they will agree and let you change the locks. When or if they need to stop in they will call you ahead of time. If not and they stop in, tell them you're busy and it's not a good time. At that point you can move things around if needed. but you should do like me and just bury your tent under junk and act like it's nothing. If they see it and ask just say oh thats a bunch of junk tell them it's an old wardrobe filled with garbage if they keep pestering you. Don't let them look inside and if they persist act irritated in a rude manner ask them if you can look through their personal property afterwards..Just don't let them look inside!