We use Smart Strings for alignment, and I have camber and caster gauges we use as well. The smart strings "hangers" don't play well with Spyder and 904 hoods, so often times we have the Smart Strings aluminum bars set on 4x jack stands. Look at their products and something like that would be very easy to duplicate with a few lengths of pipe.
And before anyone laughs at this set-up, it is used by some of the largest race teams out there, cup cars, LMPs, GPs, etc...
I didn't read the entire alignment thread so may be something you are doing or already suggested, but if you do not have some sort of "slip plate" under the front tires, do that too. We use actual ball bearing slip plates but you can get a VERY similar result with a couple of vinyl tiles placed face to face. you just need to reduce the friction of the rubber on the concrete when setting tow. You'll get a much more accurate result this way, eliminates "spring back".