Rotating Quadrangle in astropy?

Question

I have been attempting to overplot a Quadrangle on a map that I have to replicate a slit with data on the sky, but I need to rotate the Quadrangle around some center point and have not been able to get it to work. Is there a preferred method to rotating a Quadrangle around some origin point?

I tried a few things:

1. I converted to pixel position origin, then applied a rotation matrix. Then I added that to my wcs transform. See example below.
2. I tried using matplotlib.patches.Rectangle with the angle parameter set, but there is potential distortion. Edit: matplotlib was updated from the initial version I was using and allows for rotation around an origin. See below.

How can I properly rotate a Quadrangle around some origin point? Perhaps there is some method that I am not thinking of.

Included are a couple of examples here:

import matplotlib.pyplot as plt
import matplotlib.transforms as transforms
from matplotlib.patches import Rectangle
import numpy as np

from astropy.wcs import WCS
from astropy.io import fits
from astropy.utils.data import get_pkg_data_filename
from astropy import units as u
from astropy.visualization.wcsaxes import Quadrangle
from astropy.coordinates import SkyCoord

filename = get_pkg_data_filename('galactic_center/gc_msx_e.fits')

hdu = fits.open(filename)[0]
wcs = WCS(hdu.header)

ax = plt.subplot(projection=wcs)
ax.imshow(hdu.data, vmin=-2.e-5, vmax=2.e-4, origin='lower')

# example used in 
# https://docs.astropy.org/en/stable/visualization/wcsaxes/overlays.html
r = Quadrangle((266.0, -28.9)*u.deg, 0.3*u.deg, 0.15*u.deg,
               edgecolor='green', facecolor='none',
               transform=ax.get_transform('fk5'))
ax.add_patch(r)

# trying to rotate
# this works, but the shape might be distorted
r = Rectangle((266.0, -28.9), 0.3, 0.15,
              label='Rectangle', edgecolor='red', facecolor='none', linestyle='--',
              transform=ax.get_transform('fk5'),angle=30,rotation_point='center')
cx,cy=r.get_patch_transform().transform((0.5, 0.5))
ax.add_patch(r)

# shift coordinates to center of quadrangle
# this does not work, but it kind of works on my own data
# though it scales improperly when I use different x and y limits
#cx,cy=(266.0-0.15)*u.deg,(-28.9-0.075)*u.deg
ox,oy=wcs.celestial.world_to_pixel(SkyCoord(ra=cx,dec=cy,frame='fk5',unit='deg'))
r = Quadrangle((266.0, -28.9)*u.deg, 0.3*u.deg, 0.15*u.deg,lw=0.1,
               edgecolor='orange', facecolor='orange')
td=ax.get_transform('fk5')
tr=transforms.Affine2D().rotate_deg_around(ox,oy,30)
#r.set_transform(td) # same as example
r.set_transform(td+tr) # this pushes the Quadrangle off center
ax.add_patch(r)

# I am attempting to do something like this
#cx,cy=r.get_patch_transform().transform((0.5, 0.5))
for p in np.arange(-0.15,0.15,0.05):
    r = Rectangle((cx+p, -28.9), 0.05, 0.15,
                  label='Rectangle', edgecolor='white', facecolor='white', linestyle='--',
                  transform=ax.get_transform('fk5'),angle=30,alpha=np.abs(p),rotation_point=(cx,cy))
    ax.add_patch(r)

#ax.grid(color='white', ls='solid')
ax.set_xlabel('Galactic Longitude')
ax.set_ylabel('Galactic Latitude')
plt.show()