You could position satellites at the L4 and L5 points in Ike's orbit (I think; I am not actually fully certain that that is out of range of its SOI) - however, L4 and L5 points are not actually simulated so you would simply have to time a transfer well enough to get close to those points (or at least, to the places where they would be in a more realistic situation), and then match the orbital period to Ike's orbital period precisely enough that your satellite is not likely to drift and be captured by Ike at any point in the near future (I use MechJeb's displays to get such precision, and I do not think it is remotely practical in stock without a readout of orbital period that is precise to the range of ±5 milliseconds).
septemberWaves's post in Kerbolsynchronous orbit was marked as the answer