Hi mspooley, somehow I missed this....sorry! I agree for a 4 month old the best scenario is to have someone come and stay with her at your (and HER) home while you're gone.
Try contacting Elaine Allison of Canine's Best -
http://www.caninesbest.com/ She holds classes in West LA, Redondo, Torrance, and Long Beach and has an apprentice program for budding instructors. Perhaps one of them would be available at a reasonable cost to come house sit your little one for you.