OK, so let me put it this way:
Let's say this guy (let's call him guy #1):

owns 40 acres of hardscrabble land from which he barely earns a living by growing crops on his land.
And let's say this guy (let's call him guy #2):

buys the 40 acres of equally hardscrabble land immediately adjoining.
Guy #2 builds a casino/hotel complex on his 40 acres, complete with gambling, free booze for losers, pure oxygen pumped into the gambling spaces to keep the suckers awake and somewhat free of the physical debilitation consequent to alcohol abuse, piped-in music (not live music: that might make people stop gambling and watch), and a luscious crew of young and pretty Ukrainian slave girls that he bought from the local strip club. Let's say a gambler manages to win big, so guy #2 sends one of his girls to suddenly get "interested" in him, and beg the winner to take her to his hotel room. Guy #2 waits until his girl has the winner's trousers around his ankles, and then bursts in to blow the winner's brains out and take back his chips.
How does your plan (should it, in fact, consist of an ad valorem tax upon realty) recognize the differential income potential between these two pieces of realty connected with their use?