The challenge with the "suits stay outside" model is that you basically need some kind of airlock between the suit hatch and the ship hatch. You might imagine both hatches get contaminated when the suit is detached. Then when you dock, that whole between-hatch space needs to be decontaminated before you can open the two hatches, because the outside of the suit hatch brought that stuff into the airlock.

Someone else linked to this: https://en.wikipedia.org/wiki/Space_Exploration_Vehicle#Spec...

edit: in that context^ search for "SEV suitport design" find NASA has written some docs on the matter, eg https://ntrs.nasa.gov/api/citations/20130013652/downloads/20...