You can disable Direct VR temporarily with a hotkey (freely configurable in the config app). The second option is to disable the positional part of Direct VR in the vorpX menu, normal pos tracking wil kick in instead. For playing seated or standing without walking that works just as well.
Smaller than 16:10 aspect ratios cause various UI glitches with or without vorpX, that’s a general game issue. There is a neat trick though to get close to 4:3 by adding a few pixels to the width. 1604×1200 for example does work. The next vorpX will do this fully automated.