Rocket Mass Heater Size for a 28' Tipi

Hello,

I have been wanting to try living in a.tipi for some time. I want to put up a 28' tipi with earthen floor and a rocket mass heater like the picture, in northern Maine. I'm looking for any advice on this project and specifically the size of the rocket mass heater you'd recommend. Here's a link to Paul Wheaton showing one he put up in an 18' tipi.    I would also likely put radiant floor heating inside the earthen floor for added heat.


Brand new to this so thanks for your input!