There is another way....the mickey way
When the monorail goes through Epcot, flex your muscles and open the monorail door. Then, parachute down and catch the lucky wind that will blow you across the water straight into Germany.
Hey!!!! If Mickey can do it, you can too.
ok..... if you want a serious answer:
3:45 FP, assume you are done by 4 and start heading out.
Catch Monorail to TH by 4:20.
Catch Monorail to Epcot by 4:45 (assuming a little wait)
Assuming a mid to large crowd, thru the Epcot gates by 5:20
Assuming a good gait, at Germany by 5:35
As you can see, with some buffer time, you may make it to the ADR, but it is cutting it so close, the stress would be too great. I have seen a vacation almost ruined by someone in our party trying to get everyone to hurry up and ending up causing un-necessary stress. So, even if you could do it, cutting it so close may cause issues. I personally would move the ADR by 30 mins.