How to add 2015 NAIP Imagery for Pennsylvania to JOSM

I can't speak for all of America's Bing imagery, but in Pennsylvania, the imagery is often horribly outdated (5-6+ years old). I've often tried to use USGS Large Scale Imagery, but most of the time it's so slow that it's unusable, or will just load a handful of tiles and just quit working. (This seems to be a server-side issue.)

So I tried to add the 2015 NAIP imagery for Pennsylvania, using the tutorial here for the WMS format. I went to this page, clicked on the Pennsylvania link, and selected WMS at the top left to be taken here. I then took that URL and followed the directions in JOSM, clicking "Get Layers", selecting "Pennsylvania_2015_1m", and selecting "image/jpeg" as the image format.

After clicking OK on the popup and the Imagery preferences window, I went to add the imagery layer. However, I got a popup about some kind of wrong projection:

The layer gis.apfo.usda.gov: Pennsylvania_2015_1m does not support the new projection EPSG:3857. Supported projections are: CRS:84, EPSG:0, EPSG:4326.
JOSM will use EPSG:4326 to query the server, but results may vary depending on the WMS server
Change the projection again or remove the layer.

After clicking OK to enable the layer anyway, nothing apparent happens. When I zoom all the way out to view the entire world, the right half of the world is black-covered, with what seems to be three tiles appearing to the right of the edge of the world, only appearing as the red error "Error: Could not load image from tile server". At first I thought maybe the offset was just way wrong or something, but zooming in at various places does nothing.

What is going on with this, and why do I get this error despite following the instructions to the letter, with no mention at all of the possibility of this error? How can I make this imagery work in JOSM?

EDIT 1: See comment of mine below...