Not really. If you scale it then you scale it. Its bound by the gui placement.
WSYWIG would require you to wait for each update for as long as it takes to render. With 10 minutes renders its not feasible. So instead of WYSIWYG they give you something even better. they give you What You See is Far Vetter then What You Need to Get it Done.
2 things:
first
You mean resolution gate. this will draw a internal box in the viewport that will be in shape of your cameras resolution gate.
Now the gate fills the view and you can dim out everything outside the gate by editting
in maya >2009 theres a option
AE-> Camera Template -> options display gate mask -> set it to black and opacity to 1 prevents you form seeing whats outside.
Using the film gate and postional offset its possible to zoom into parts of a film gate if you wish. Without actually affecting what renders. So no the gate does not have to fill the entire viewport.
In all mayas:
Someties if you have a very wide camera gate yoru fitting it on the worng axis. set the finm back fitting to -> overscan
Now then if the gate is too form fitting for your need and you have hard time seeing where it starts.because it skims too closely the the viewport. Adjust the overscan setting under the same area set them to 1.5
second:
use a ipr render. And use arrow cursors to move things in the furstrum. Also its possible to pick a location in the rendered view and postion based on that. (its just simple trig to figure out)
I frequently have to create animations to drop onto pre-existing
backgrounds, and I often endup having to do a lot of >> back and forth to
get things to render in the correct position
Your workflow is unoptimal. Use a image 3d/2d tracker. That way you can select the actual position form within the image so you dont need to guess anything since its where ist actually supposed to be in pass 1.
Its not like you can say you cant afford such a tool. as they cost less than you doing one extra day of work.