With the demise of Penn Lyon, I was afraid we'd never see another modular house with R40 SIP walls. Luckily, it seems other companies are now starting to offer this.
Be warned... I know nothing about the following companies. I mean it, nothing. I am not certain if they can or will build you a modular house with structural insulated panel walls. I am listing them here now because I have been told they will. Since Penn Lyon is out of business, I am hoping that someone will build a house like this for you.