Id be wary of using anything that looked like pot or smelled like pot , itll only draw attention to it.People dont give tomato plants or corn , peppers any of the vegetable plants much of a second look.Its a vegetable garden..end of.Its a good place to hide a few plants.
Theres been a couple of incidents recently where raids were conducted on homes where neighbors had reported seeing those pot lookalike plants because they thought it really was.
Its never going to be invisable,but care in how and where you plant the plants that will conceal it is what its all about.Tomato plants work well because they are tall and bushy and leafy , plant 3 or 4 of those with a 2 foot spacing in two rows , like square shape or triangle leaving a what looks at first big space empty in the middle , thats where your pot plant goes.Tomatos grow very rapidly , lots of coverage.Eventually the only way it can be seen is if you know its there.