Sorry for the delay. What you are describing can definitely be done with the remote. You can save 3 different profiles that include whatever settings you want.
The settings available to the internal scaler include:
Fullscreen
Stretch but maintain aspect ratio
1:1
Emulate random screen sizes (useless)
It takes about 1.5-2 seconds to switch modes. I don't know if that is good or bad to your standards, but I will say it is INCREDIBLY ANNOYING for the initial setup. Instead of navigating to the picture mode you want and selecting it, it selects a mode every time you scroll up or down the list. What were they thinking. After you get that out of the way its no big deal though.
Something you could try would be having the GPU "Software Scale". I know some cards are able to just add those black bars around a picture so the resolution the monitor sees is 1920x1080, but the OS thinks it is 1280x1024 for example. This is very useful to monitors that are not able to turn the scaler off.