Hi Eric
If your goal is to work mobile while driving, your windows of opportunity are going to be slim. I've done it, but effective air time will be pretty short. On the portable side, I've been able to achieve VUCC Satellite using 5 Watts FT-60R handheld and an Arrow antenna mounted on a photo tripod standing on the back deck. I also have the Elk but school's out on which I prefer (for me- but most guys prefer the Elk). I've also built K5OE's Eggbeater II for 2 meters which I have mounted in the attic along with an antennas.us quadrifilar for 70 cm. Preamplifiers on both. Results are OK but not as effective as even a simple directional antenna. I suspect that the weak link is the quadrifilar and if I mounted a homebrew Eggbeater for the downlink, it might improve results. Have also built EA4CYQ's "IOio" handheld combo which works very well also. Go to http://www.eb4dka.tk to see some great videos on how they work. Simple to build and effective for portable work. Good luck.
73 Marc W4MPS (formerly WA2S)