Dual DC/DC converter in Model S

[CookieMonstar]

Hey everyone,

I hope you can help me with an idea I'm working on. Currently, I'm planning to purchase an older Tesla Model S (2015) to tow a caravan. I'd like to use the Tesla HV battery to provide complete autonomy to the caravan. Inside the caravan is a 7kWh LiFePO4 battery that could act as a buffer and needs to be charged by the Tesla. Considering the power requirements for heating, cooking, etc., it's clear that using the Tesla own DC/DC converter is not feasible.

I've been thinking about whether it's possible to install another DC/DC converter and tried to find information on this, but unfortunately, I couldn't find anyone who has attempted such a setup. Also using an additional converter could offer better control over the charging voltage.

Here are a couple of ideas I had:

Option 1: Install the second DC/DC converter in series with the original one in the cooling circuit and operate it only when the Tesla is on. That should theoretically be sufficient since the battery in the caravan easily gets me through a day. With the full 2500W of the second converter, the buffer would also be fully recharged within 3 to 4 hours (If I haven't miscalculated).

Option 2: Find an alternative cooling solution and operate the converter independently. This might be more efficient as it saves the Tesla's power consumption. However, significantly more complex and requires more space. Moreover, I'm not sure if I can do this at all as the HV-relays are not active, right?

What are your thoughts on this?
How could the cooling issue be addressed?
Would the original cooling circuit be sufficient, or would something overheat?
Will the Tesla throw errors if power is diverted in this way?

Thanks in advance for your input!