Stretching grips

I’ve read to grip 1” below the glans head. Is the glans the only part of the grip to worry about?

Any problem gripping at the base to stretch?

It’s not mandatory at all that you grip any certain distance from the glans or the base. You can vary your grip and just see what works and feels right. If you grip more towards the glans, you”ll stretch tunica more (although, depending on the angle of pull, you can also get the ligs good too.) If you stretch towards the base more you’ll be hitting the ligs most directly.