Heat treatment - moist towel

[Reascot]

I'm using a moist towel and a hot water bottle as a heat treatment. But I worry that it's not properly heating the whole penis. Does anyone else do something similar?
I might switch it to a sock with rice and a toilet paper roll to hold it in place.
How long on average do you guys do the heat treatment?
I've ordered a VED so will start using that after a heat treatment.