These responses from Signature Solar are not inspiring confidence. The product description says "reliable Built-In BMS, Voltage, Current, Temp. and Health Management." But in the above response regarding official support for RV/mobile applications it seems there is some expectation that the BMS might not actually prevent under-temperature discharge or charge. If that has been tested and tested to the point you can say "reliable BMS" on the website then it shouldn't even be a question, concern or caveat. In another response heat tape was mentioned. Heat tape is great to raise battery temp so operation can continue within temperature specifications. But that doesn't really address the accuracy and reliability of the BMS thermal question. I could see language stating, "so long as BMS temperature protections are not tampered with or bypassed so as to allow discharge below 0 degrees or charge below 32 degrees..." The only question should be the BMS failing, which is still a warranty issue.
If a lithium power system is engineered excellently and thoroughly and operated very precisely, the only need of BMS is for cell balancing. All the current, voltage, and temperature protections are needed because we're not building power supplies for critical systems in medical, scientific etc. We're on vacation in a camper using a power system budgeted accordingly. Sometimes unexpected things happen. I don't want to worry about my battery taking massive damage because it got colder overnight than the weather guy predicted and not ABSOLUTELY KNOW that the BMS is going to come through for me to shut down the battery. I'll just go without before risking such a financial loss.
I don't take pleasure in being so blunt but spending such sums of money is a serious matter regardless of income.