Hi Robin, one possible solution if you use Invites.
Create a user group say “Practitioners” you can also add members manually when needed. Have the group setup to bump Trust level to 2 or 3.
Automation plugin included in core can also likely use a script based on a user Feild to bump to or add to group.
May still need to check with team to see if TL2+ is not affected by viewing user list. However if the group allows members to view members of the group this might work as a workaround to the site setting(would need to be tested)