just curious, what will you be using the TS parameters for, crossover design, or a woofer enclosure?
If its a woofer enclosure, you can get away without knowing the paramaters by estimating the woofer's resonant frequency, then building a transmissionline-based enclosure. You can estimate the woofer's resonant frequency by using an SPL meter + frequency sweeps, or via a realtime analyszer rig + pink noise. The lower frequency at which the amplitude starts to decrease dramatically is the resonant frequency.
If its for crossover design, you would really need the parameters.