I truly hope your setup works as intended. I'm very interested in your test-trial results.
The concept is ideal; with no on-board mix-tank and what is effectively a closed-system that minimizes potential applicator-exposure. A true win-win in for both efficiency and safety.
My efforts with a similar system didn't pan out as I hoped. Adding any type of downstream restriction; such as a fire-hose nozzle or connecting to smaller dropper-hoses, caused the pressure to equalize throughout the system's piping - which disabled the venturi-inductor's "draw" from the concentrate-reservoir.
Should your venturi fail to draw fluid from the concentrate-reservoir (while the downstream ribbed-hose is coupled to the transom-mounted dropper-hose boom), maybe try disconnecting the ribbed-hose from the boom's tee-feed - since that would be the point of a potential restriction - and then see if induction from the concentrate-reservoir is achieved.
Yes, those ribbed suction-hoses are indeed pricey (often $4-$6/ft). They're typically used where the fluids within are under a vacuum rather than pressure. The integrated ribs prevent the hose's collapse under a vacuum.

Kelly Duffie
Cypress, TX