Hej Otto!
You are indeed left with the bases Såtenäs, Linköping and Ronneby.
As Erwin told you, those are the spots you can stand at those bases. However, photographing of military infrastructure is not legal in Sweden and you should be carefull. It is allowed to take photos of aircrafts but not towards the base.
Nevertheless, Ronneby and Såtenäs seem to be a bit more relaxed with regard to that and it should be fine to do some spotting there. Linköping-Malmen is a different story... there is also the SAAB factory at the civil airfield of Linköping, but that is even more "dangerous". You may want to have a quick look there though.
At Linköping-Malmen you can also stand at the parking lot of the Airforce Museum on the north side where you have a view on the approach, if winds allow.
Anyways, at any base when you are standing along the fence, most likely you will meet some security. Depending on their mood they will allow you or send you away.
Flying activities are as nearly everywhere in Europe: normal flights during weekdays, only Fridays it is less activity and they may stop earlier. Best chances are tuesdays, wednesdays and thursdays.
Usually, they will fly 4 times a day, starting at 800/830 to the last mission around 1500/1600.
Hope you enjoy Sweden and any other questions are welcome!
Corné Uittenbogaard