My brother, who is quite accomplished in gardening, told me he starts/grows new plants in a south-facing window. While the east-facing, laundry room window from where the seeds mentioned in my last post were started never struck me as optimum, it was the best heated space available at the time.
With the weather warming up, the stagnant seedlings were moved out to the unheated Shop's south-facing window with the hope the seedlings would get better light, and harden at the same time.
In short order, it was obvious this window has better continuous sun. The latter part of the first day was aided, I'm sure, by reflection from the Airstream. But that was temporary - my American Classic was subsequently moved back to its usual roost.
Suitable support for the Jiffy Greenhouse was provided by the window sill, and my Overlander's original Univolt (with battery simulator) perched atop the Shop's lathe.
I sure am glad I did not listen when everyone suggested making a boat anchor out of my fully-functional, ready, willing, and able to overcharge a battery, Univolt.