When I was young--even around 8 or 9--when my mom would spank me and my brother, we would have to pull down our pants and our underwear and bend over...
I used to use Vaseline and rub it all over the outside of my pucker and then try and get it greased up inside too and I would start fingering myself...
The length is not the challenge, that only limit how deep he can enter you before you feel pain or discomfort, although with care and time he can get...
Not a continuous sucking butt I have had sessions of 2 or 3 hours where a guys cock was presented to me by a Dom to suck on, it was part of the tease...