Dogs obviously, visibly cold in mornings—ideas for crate solutions?

Husband and I are living with my parents for the winter while we save up to buy a house. We’re in the basement (yes we have carbon monoxide detectors!) and our dogs are crate trained in wire crates. We’re having a bit of a disagreement over thermostat and parents aren’t budging on making it warmer. Space heaters are nonstarters due to fire risk, which for us is elevated in the basement since there are no windows and only one egress (I have several strategically placed fire extinguishers, for anyone worried about that lol)

Problem is, both dogs (8f shih tzu 11lb and 7m terrier mutt 21lb) have woken up shaking, even my boy sometimes with his undercoat. We have jammies on them and cover their crate with blankets for greenhouse effect and have blankets inside but they’re cold! On bad nights we let our girl in bed with us with our heated blanket but there just isn’t enough room for both of them. If we let them sleep outside crate they’ll just hop in bed with us at 3 am lol (our boy is especially cuddly, he is so stubborn to leave and my vice is I give in to his adorable grumbles, which always wrecks my sleep for that night).

I have a couple ideas but don’t love any of them because of various concerns so wanted to crowd source opinions:

-heated blanket over crates instead of normal blanket. Worry is even on lowest setting, surrounding air will be too warm and they won’t be about to escape heat. FWIW during the day, boy is obsessed with laying on our heated blanket, he loves being toasty! Girl gets over it after a while and voluntarily leaves our warm nest.

-heating pad between their two crates, (but inside neither). Their crates butt up against each other with solid, thick lining between so they can’t see each other…thinking of replacing that with heating pad. It will give them space to move away from direct heat source, warms the area instead of a spot, but worry about wire metal getting too hot plus same concern of heated blanket that it will warm the air too much

-microwave disk things, I’ve seen these recommended on this sub but I worry by morning it will wear off and they’ll be cold again, since this is our original problem… they’re fine when going in but slowly get too cold and wake up shivering

-body heat reflecting pad, which doesn’t use heating element which is good but they still wouldn’t be able to escape it if they get too hot plus worried the crinkle will make them treat it like a toy and chew on it (boy chews crate blankets when anxious, girl goes absolutely feral for crinkle noises in toys! In summer boy gets just a durable mat but he gets blankets in winter with very close eye)

Maybe I’m overthinking all this but none of these sound like the right solution so I’m hoping there’s something else to consider that I haven’t thought of!