I am planning to take a train from Fussen to the Frankfurt airport on Sept 25 in the cheapest possible way and this is what I have come up with:
Take a regional train (are trains marked as "RB" regional trains?) from Fussen (Main) to Augsburg Hbf on my Bayern ticket.
Take an ICE from Augsburg Hbf to Frankfurt(M) Flughafen Fernbf. Problem: this train is showing one change at Mannheim Hbf for 7 minutes where I will have to change from Platform 2 to 3. Do you think that is doable with at least 15 kgs of luggage with me in 7 minutes?
Is there a cheaper way to do this without too much discomfort and too many changes? Thank you all for your help!