Hi Matt,
Continuation of IBT is essential, especially where varicose veins are a problem. So intermittent IBT is counterproductive, two steps forwards, one step back.
You right about compression on bottoms of feet, from standing in one position. This can be countered by gently shifting your weight from one foot to the other, to help with pumping action.
A steeper angle will inevitably cause you discomfort, possibly loss of sleep too and then there is an increased risk of tissue damage, due to increased shear forces on skin.
Sitting, with knees lower than seat is better, but not ideal due to compression of buttocks for long periods of time and no doubt there is also pressure on backs of thighs from chair.