45 min should be OK for you and luggage.
As far as I know you can follow transfer signs at domestic and go upstairs inside domestic area. That is much faster than exiting domestic the usual way and wait in line for security again.

SAS will check through to final destination if both flights are SAS, even if different tickets. Consider what to put in carry-on vs check-in luggage and have your travel insurance policy ready if luggage don't make the connetion.