I take it that you are a fast runner at the shorter races then Livia to go for a sub 3:45 for the first one.....and have been running a few years..........
so you know your long runs aren't going well......i would think that 3:45 is going to be a tough ask....but there again if you are a fast runner over short distances and young then maybe you can prove me totally wrong....hope so..........
you need to get a few runs in over the 30k .. but you also need to let your body recover form the bugs or your immune system might be low and you pick up a third......
so your plan looks ok but i would be really careful of the next one the 28km one....and really slow it down and don't push it all at.........even shorten it if you don't feel right...........
if you feel ok the next week then carry on with the 30km
good luck.its horrible when illness gets in the way of training 