For anyone who might stumble upon this thread in the future; We now managed to do S35.
The AOU guide is a little misleading as there's no problem for an enfo to do mongo, and you only need one of the 3 towers to survive.
We had no problems keeping enfo alive, but he needs to be on his toes to mongo aliens off of the tower(s). I think the best strategy is to concentrate on one tower and make sure it survives. Can probably more or less ignore the other two.
The hardest part with S35 is by far the waves of aliens. Once the two bosses spawn, you'll be hard pressed to fail. They are rather gimpy compared to the other sector bosses. AOU suggests two tanks, but that is really not necessary. Kill support boss first, then the marshal. The marshal seemed to still have reflect up a good while after support died, but eventually it disappeared and he went down without much trouble.