In order to pass that section would will need:
1) Rogues: The Bonus Contents in the game use the PvP AI, so rogues are automatically the first units they will go for. Take advantage of this and use 1 InA/PE and 7 rogues to take 7 extra hits without a scratch. (Note you may not have access to rogues, so this is optional only for that reason)
1) Howitzers: Only the first one or two provinces will work by using InA units, and you will need to take advantage of that howitzer as much you can.
2) PE Units: Once you reach the 75% sectors, you will need to use PE units to get anywhere in the map. Take advantage of their range and the new terrain. Snipers (and RFC) can hit howitzers without them ever reaching the snipers. Tanks will take care of lancers and snipers (yet again) will have too much defense and a unit bonus for jaegers to scare them.
3) Infiltration: I totally forgot about this until I hit the PME and was stuck using my non boosted ME units against two waves of ME and PME units. This baby takes care of 10% of the damage which is really useful in the long run if you can't get past it.
4) Goods: if you tried and tried, but just want to give up fighting through the Bonus Content, then surrender by negotiating with them
5) Offensive GBs: Since I said that I got through everything with non boosted units, I don't really need to recommend this, but the Statue of Zues, CoA and CdM will help alot facing these overpowered units as well. With a strong enough boost, you probably can take the sector without any PE units