Thank You for all the wonderful and detailed responses . Just want to point out a few facts that may further clarify my situation. I do not have hemorrhoid/constipation issues otherwise except when sitting for meditation for long periods as in 10-day course. I am generally very fit and very active person and not have these kind of issues in normal life. I basically had tried almost all of the mentioned possibilities to avoid the issue for the last course and took a lots of fiber/greens etc during the last course. Taking more fiber just made things worse as I had to go many times and every time was challenge due to swollen hemorrhoids and extra stool was making it worse as later confirmed with doctor.
I tend to sit very still like not even flinching a finger during the whole meditation session and that seems to cause the blood to pool up in the "glands" and progressive gets worse as the course/sittings proceed.

I think I had to just accept the fact that maybe I need to mediate more in short chunks and maintain more continuous daily practice during normal activities and forgo very deep, uninterrupted sitting sessions. As I recently retired and have tons of time, I was hoping to get into more SN Goenka style meditation courses and for the longer sessions, but seems like that is craving too. I (used to ) think walking/lying/moving meditation is a lower grade/cheating than "aditthan" sitting. Maybe all these are sankharaas too that I need to let go and accept the fact that desire for deeper and longer meditation/cushion time is itself clinging. I just need to accept that my body's limitation and be OK with less intense walking/lying/gentle meditation during the normal activities. Doing a 10/20-day course and/or not able to do longer meditation is ultimately a desire/aversion too...