Worrywart?? Nah, there's nothing wrong with being careful and vigilant with a cusom built vehicle, especially the first few hundred miles during "shakedown". If bumpsteer hasn't been a factor yet, it is probably a non-issue. As Dave intimated, the less the front end travels (up & down) the less a factor bumpsteer will be.

I still am skeptical of that Pittman arm. Any welding I do on steering components ALWAYS gets gusseted or reinforced somehow. Also, your builder cut and welded it at the splined end which is where it suffers the most stress. If it ever breaks, it will probably do it without any visible forewarning. Maybe I'm the worrywart, but I had a steering shaft snap at a weld in one of my stock cars years ago. It was the ultimate "Oh $#!t" experience; the concrete wall was not very forgiving at 70mph. I would hate to have that occurrence on the street...

Having said all that, though, driving a lightweight fenderless vehicle is about the most fun you can have on the road, right?