I wear one of these in all my Moggies during our rather cold winters here in the Rockies, works great under all types of clothing and is controllable:

https://keisapparel.com/products/heated-vest-premium-v501


Bruce
1964 4/4 Series V Comp (Megan)
1994 +8 (Maurice) tis no more
2013 M3W (Olga)