I'm planning on moving from Washington state to Phoenix

I'm in the same boat OP.

Moving from Chicago to Fort Collins in June and me and the gf aren't renting a moving truck. I drive a small car so we are really downsizing and throwing everything away beforehand, which is okay since all we own is fucking trash. We're planning on renting a small Uhaul trailer for some of the larger things that don't fit into the back of a small hatchback.

As for renting an apartment before hand, you have to call and ask around if they'll accept applications from someone so far away. Depending on the location apartments might not stay on the market for long at all. I worked in real estate before here in Chicago and all the nice apartments we had, ranging from about $1200 to $3500 a month never stayed available for more than a week before they were rented out. Best bet is trying to find roommates and creating a record of living in the area before finding your own place.

Before moving, throw away EVERYTHING you haven't used in a while or plan to never use before.