Interesting write up. Seems you took the vipassana thing as a challenge. A few things irrespective of where you do so:
- Remember to eat less (your 75% rule is good) but also make sure you get enough exercise throughout the day. Use the walking meditation as exercise.
- Correct posture is VERY important. Your knees and the pelvis must form a triangle with knees below and the posture slightly open. Otherwise it hurts. If you prefer use a seiza bench. Once it hurts, meditation becomes very painful.
- Learn to enjoy the process.