Don't Know What To Do?!?

As I have mentioned before, my walking buddy and I are training to do the half-marathon in June. Well, Hubby and I have been asked by our Stake Presidency to be a Ma and Pa for the trek this June. The HM is on June 13th and the Trek is on June 18-20th. I don't know if I physically will be able to do both, but don't want to give up on the HM. I will have 5 days before the Trek, but on the Trek we are having to walk 7-8 miles a day. Do you think I am crazy if I do both?? Should I train for the HM even if I don't do it? Do you think it will help me for the Trek and that I should continue to train? UUGGHH!!!!