When performing a similar type of calibration and validation, consider the following recommendations:
Obtain test data from at least two (and preferably all three) of the experiments in the hyperelastic test suite.
Ensure that the test data covers the range of deformation over which the constitutive model will be used.
If the error between the experimental data and the constitutive model is too great, try limiting the experimental data to the range of deformation over which the constitutive model will be used.
Use the constitutive model within the range of fitted data only.
Use an independent experiment to validate that the constitutive model adequately matches the material behavior.