I had neglected to check to see if there was a better way to initialize these. In fact, pseudo_1 can be set to the pmtank3t temperature to start since they are generally within three degrees of each other (Celsius). Pseudo_0 varies a bit more, but setting it to tcylaft6 minus 4C would put the mean error between the "correct" initial value and the estimated near zero. I'll update the model to reflect this.