I wouldn't know where to get a good lab-grade oven. I'm an amateur who deals in only VHS, so far.

I have been fortunate thus far to have not found a tape that has succumbed to these conditions. However, I do know of one place I would consider getting a lower grade one from if I had to try, based on reputation on this forum regarding his VCR refurbishing/restoration services.
https://www.tgrantphoto.com/sales/in...king-equipment Also, the article he posted on his tape baking experience.
https://www.tgrantphoto.com/sales/in...ng-video-tapes
I suppose you could make the same item as he does for a bit less by adding a thermostat to a food dehydrator. But I tend to think he's done this before, and I'd rather spend a bit more to get one from somebody with experience, understanding that it is still something you do at your own risk. I think the advantage to his approach is that you are not just trusting an off the shelf commercial food dehydrator to maintain the temperature tolerance. The thermometer idea would seem to be a very wise feature so that you can adjust the dehydrator if the setting doesn't match the temperature advertised, and also to keep you in the sweet spot of being just enough and also not more than necessary, to avoid doing any harm.
As the initial Library of Congress research found, there is a rather precise minimum temperature you must maintain to affect the tape's chemistry, at least for audio tape. Although that research hasn't mentioned any temperature for video tape yet, it seems to be on the horizon as their studies continue. I suppose the informal trial and error numbers circulated on the internet by other "bakers", or in the article link in the first paragraph of this post, would seem to show a very similar temperature when compared to the audio tape temperature from this initial phase of their study.