I was just thinking about that fact like, yesterday :D
The thought process was something like "dang, I should have practiced Blender more during the late '00s/early '10s
->
I probably would have gone crazy with those mouse bindings" :D

going all the way

Or... evil option... make the viewport rectangle also be filled solid.

Apart from just drawing it in wireframe while in wireframe viewport shading mode, the triangle could still be filled solid, but remain a fixed size instead of scaling relative to the camera. Hell it could be both :D
Or, if you actually *like* the giant scene-obscuring triangle, it can be an option!

Yep. It's like a giant fly that is hovering around mostly unnoticed until it flies right into your face :D

I could use the outliner to select it even if it was otherwise unclickable, being able to see it is more important :D

...why are you so smart???? :D :D :D yes, I think that would work for this specific thing I'm making :D

Trying to think of anything else that floats in 3d in Blender which acts the same way, but everything else is just small, thin or doesn't otherwise obscure the scene in any way.

I'd need it to keep the shape of the actual camera viewport and the focal length "geometry" though, so it might be more trouble than it's worth :D

Yeah I was thinking of having a dummy wireframe camera constructed in geonodes that would follow the actual camera around

I actually thought of having a dummy camera wireframe constructed in geometry nodes which would then be parented to the camera and follow it around, with the camera gizmo size set to something very small like 0.001m.

At all times, unfortunately :D

I could hide the camera, but what if I need to see where the camera is in the scene? (and I usually do)

I could disable the overlay... and lose the grid and everything else? :D

c d e d b d ducks!

That was supposed to be the alt text, but hey, works as a post too.

King Arthur yelling "A DUCK" thereby demonstrating his learnedness in the ways of science.

Yep, exactly :) good thing they tolerate being aimed at with a camera :D