Using the Observer's Guide, I've noted several planetaries that have been described as challenge objects for 16"/18"in Aquila and Cygnus. Although I could penetrate to about magnitude 13.5 in front of my light polluted home last night with very good transparency and excellent seeing, the following planetaries are around 13.5 magnitude or greater and some appear stellar in surrounding star fields.
First up: PK 85 +4.1 Abell 71 in Cygnus. At magnitude 14.5, it's said to appear as a very faint, tenuous 2' disc with milky way stars superimposed on it:
Next in Cygnus: PK77 + 14.1 Abell 61. At magnitude 13.5, it's said to be responsive to an O111 filter and the Guide notes it to be an extremely faint and diffuse 2' diameter disc:
Also in Cygnus: PK 81 -14.1 Abell 78: At magnitude 13.4, it's 1.5' disc, although responsive to an 0111 filter, sits between two 7th magnitude stars and their glare interferes with it:
Moving onto Aquila, PK 40 - 0.1 Abell 53: At magnitude 15.5, it's 30" disc is said to be extremely faint although responsive to an 0111 filter:
PK 47 - 4.1 Abell 62: At magnitude 14.8 is fairly large but is situated in a rich star field:
PK 51 - 3.1: At magnitude 13.7, it's said to require "blinking" with an 0111 filter in order to be visualized at powers of 300X or more:
Well, I have a bit of a plate waiting for me at my favorite dark sky site...
PS Seeing was so good last night that I was able to use a 3.2mm x cel eyepiece, the shortest focal length eyepiece in my collection, in my 16" f4.5 dob on Saturn and Jupiter...talk about "big planets"!