Traveling while pregnant.

Okay so some back story. I'm almost 13 weeks. I have a history of 2 preterm labors one starting at 23 weeks and the other 27 weeks. One went to 36 and the other 34. I also have had 7 miscarriages but I am out of those woods now. My hubby is gonna be enlisting in the Air Force. We haven't gotten a set date for basic training yet but I will have to stay with someone while he is in because I have no family support at all and his parents travel the US in their camper. I might have to go to Colorado Springs from shelby Nc. Altitude difference if about 5000! So now my question. Does anyone know if traveling in late second trimester or early third is safe? Can the drastic change in altitude cause preterm labor? Are there any other thing I should worry about with traveling so far later in pregnancy? Please help me make the right choice here. I also have a friend in myrtle beach sc who said I might be able to stay with her. That's only a 4 hr drive from here. Idk what to do.