First thing I'd do is contact the home owner and see if they mind you installing them. Some poeple/ places will allow it as long as you leave them in place when you move out.
If that doesn't go over well, keep the most critical things up high. There's no "rules" saying you have to put the poisons under the sink, and the plates and cups up high. We keep our sharp knives in the cabinet over the fridge and in a knife block on the counter between the fridge and stove. We also keep most of our poisons locked in a cabinet outside.
If you have to, you could always replace the knob on a closet door with one that has a key lock. You can put the poisons in there after that. Changing a knob in NO way damages the property and can easily bechanged back before you move.
Hope it helps~ J.
BTW~ all quality saftey products seem to have a "quality" price tag too! remember that you get what you pay for. One of my friends put a "Window Alarm" on the poisons cabinet. She used two-sided foam tape to attach it. That way she could hear the moment her daughter tried to go in there and it scared the jeepers out of her, so she didn't like that particular cabinet after a few attempts.