Hydronic radiant floor heating

I live in Canada and due to the harsh winters I would like to install Hydronic radiant floor heating. It appears to be the most efficient way to heat your van.
It looks like Van Life Tech has built a pretty solid system but they’re not giving up any of their secrets.

Does anybody have any idea what furnace I should install, webasto or espar?

If anybody has installed their own hydronic radiant floor heating in there van I would love to find out if I need to somehow cool the coolant before it goes through the pex lines in the floor and how one might do this.

Any information or photos of a build on this topic would be super helpful.

Thanks in advance
Michaeltransit