Steve --
Gunter Spitzing in The PhotoGuide to Effects and Tricks, Amphoto 1974
has a section on close up diopters on a Horizont, forerunner of the Horizon 202.
He had an optician cut 16x16 mm squares of +1, +4, and +10 diopters and mounted them on the UV filter for the camera w. adhesive tape.
You'll have to check whether the focus of the Horizon and Horizont are set at the same distance.
For the +1, he gives a focus distance of 1m, just as you would expect from any lens set at infinity, with a +1 diopter. He does not provide dof figures w. the diopter in place.
For street, you might want to try +0.5 and +1, and play w. the aperture.
Remember that the limited depth of field at larger apertures will be curved portion of a cylinder.
Couldn't find your section on close up lenses at your link, europanorama.