i feel your pain
i tried working in 45 - 47 and the most i could do was 3 hours then ........ under a cold shower and zzzzzzzzzz on the sofa . lights out.
but if you want real pain , try 63 degrees celcius welding inside a confined space pressure vessel .
6 - 10 minutes on , 20 mins off x 3 cycles ......... cold shower again . lights out 8.(
that nightshift idea sounds like a goer ?