Yeah, I think you'll really need a fresnel to be able to work with this comfortably. It's really awkward to have to bend over into the far corners to see what's going on along the edges of the image.
I can't say whether the €185 fresnel is worth it. You can buy general-purpose sheets of fresnel material and cut that to size, which will probably be (a lot) cheaper. Then again, given the total cost of the new setup, why bother? Just order it with the fresnel included so you know everything fits and you can reach out to the seller if it doesn't work well for some reason. We're talking about 7% on top of what you're already paying. Peanuts.