Yes, that was my original idea, and it appears that my thermo bottom housing similar to yours, although I think mine is cast iron, not alloy. It has a flat area where your heater outlet is, but it isn't drilled.
https://photos.smugmug.com/Land-Rove...%20housing.png
When the new thermo arrives I'll see if there is room to install it there, otherwise I'll make an adaptor in the top hose as JD suggests.

