You might want to ask here about your river crossings along the route if you don´t have got anyone involved in your trip familiar with Sarek.
I hope that one river you mention isn´t the Rapa river (Rahpaädno on the map). There is only one place to cross it and you have the odds agaist you in the beginning of July, given that if the water is high you definitly can´t cross it even there.