Hitch 5 Bike Rack

I have a 2002 CRV and need a way to carry my bicycle on an upcoming cross-country trip. I need to be able to access the trunk space so I don't think I can go with a hitch rack. I have a spare tire, however I can't say I have the utmost confidence in one of those systems keeping my darling bike safe at freeway speeds. I've been interested in using a roof rack, however, I'm not so sure how well that system will work for me in the long term. I'm only 5'6", so I couldn't see getting a bike on the roof being very easy even during the best of times (not to mention when I'm exhausted after a long ride.) Another concern of mine is trying to keep my bike out of the hands of a stranger who may want to "borrow" it when I'm not looking. I thought about the roof rack for this reason; it may not be a robber-proof system but at least it'll make it harder for someone to get the bike down, and thus hopefully make my bike a less attractive target. Any help is greatly appreciated!