Poser is starting to get squirrely on me.  It is whiting out when I try to make adjustments.  I hope I can get some more scene elements in here without it locking up on me.  I need to learn how to do external runtimes.

Sadly external runtimes won't help you here. The fact you can see "whiting out" says what you've got is a very old, and well known problem, with Poser running out of memory.

Some solutions to this are...

Before using poser, reduce some of the texture maps in sizes. Say from 2048 down to 1024. Obviously, if you are rendering large you'll loss quality this way, so reduce the textures that will be at the rear of the scene.

Also don't forget to BACK UP the original BEFORE any reduction. I often reduce maps like this and just leave the zip file in the same directory as the originals. That way I don't lose them.    

Poser isn't just a memory hog, it's an untidy beastie. It doesn't exit clean but leaves stuff hanging around in memory. So don't just restart Poser after it bugs out, restart the machine then use Poser before anything else.

A general cleanup of what stuff loads when the computer (mac or pc) startups can also help.
That should be done anyway, as you don't need stuff like itunes, skype or adobe starting when the machine does.
Renoving these from startup will always make a machine faster.

These problems will also get worse when you try to add more elements.
So theres 2 tricks here to fix that...

Firstly, try rendering your scene in segments. Save the camera position first makes this way easy, though remember watch out for the shadows.

Second approach. Render the environment your truck will live in, but don't add the truck.
Take that render and apply it to something like the Infinity Cove, Nerds backup or my free DSU prop.

Pinky - you left the lens cap of your mind on again.