Sure, a strain guage is perfect for this type of application, plus you can stick it anywhere on the bar as long as it's aligned properly, unless its a 3 axis guage. Not sure if/how well it'd register the shock loads though.

Are you recording lateral Gs? That'd be an interesting comparison for all these links! I don't think those rear toe rods see squat for loads. I wouldn't put any faith in there being a design basis for the aftermarket ones by VB&P, etc. If they guess at it and overbuild it by 1000%, it'll never break, and therefore the design will never be reconsidered.

I'd like to see if they even load up much when you hit a curb or bump strip.

Question though, don't you run into length limitations on the strain guage wiring?

The equations given here for the Wheatstone bridge circuits assume an initially balanced bridge that generates zero output when no strain is applied. In practice however, resistance tolerances and strain induced by gauge application will generate some initial offset voltage. This initial offset voltage is typically handled in two ways. First, you can use a special offset-nulling, or balancing, circuit to adjust the resistance in the bridge to rebalance the bridge to zero output. Alternatively, you can measure the initial unstrained output of the circuit and compensate in software.
The equations given above for quarter, half, and full-bridge strain gauge configurations assume that the lead wire resistance is negligible. While ignoring the lead resistances may be beneficial to understanding the basics of strain gauge measurements, doing so in practice can be a major source of error. For example, consider the 2-wire connection of a strain gauge shown in Figure 8a. Suppose each lead wire connected to the strain gauge is 15 m long with lead resistance RL equal to 1 W. Therefore, the lead resistance adds 2 W of resistance to that arm of the bridge. Besides adding an offset error, the lead resistance also desensitizes the output of the bridge.

You can compensate for this error by measuring the lead resistance RL and accounting for it in the strain calculations. However, a more difficult problem arises from changes in the lead resistance due to temperature fluctuations. Given typical temperature coefficients for copper wire, a slight change in temperature can generate a measurement error of several me.

Using a 3-wire connection can eliminate the effects of variable lead wire resistance because the lead resistances affect adjacent legs of the bridge. As seen in Figure 8b, changes in lead wire resistance, R2, do not change the ratio of the bridge legs R3 and RG. Therefore, any changes in resistance due to temperature cancel each other.