Yes you got it, even if I’ve spent the last couple of days doing exactly that. I’ve done this journey a couple of times already but over 3 days/2 nights because I wanted to do it as quickly as possible because of work. Now I’m not working anymore I can take my time a bit more.
More stops mean more checking and you really do have to cross-check everything. A couple of years I had a problem with a hotel in Salamanca which hotels.com had said was dog-friendly but it wasn’t!
I was under mistaken impression that this site was full of b&b owners desperately waiting for my valued custom 
I like staying at British/Irish-owned places as well, I don’t get to speak much English these days and they often do a decent breakfast which keeps you going a whole day.
You might find more luck on Facebook?
I have done a similar trip every year for the past 15 years, I take my pet cat and my first stop over the
border is Pamplona.
Use Google earth to itemise the hotels/hostels (Spanish for hotel). I have staid at various hotels over the
years but my favourite at present is Hostal Izaga near to the airport at Noain. I book on line, about
40/45 euro, 2 blocks away from the hotel are 3 petrol stations with diesel at 1,48 litre.
It has a nice restaurant with menu del dia.
Do NOT visit the area on Sundays as most restaurants are closed
Why not check out a site specialising in B&B… there are lots.
e.g.
I can recommend L’Excess Brasserie/Hotel in Vierzon…not too far from Tours but whether it fits with your route I cannot know. Simple, clean, easy to find,car park opposite and evening food is fine. Breakfast is extra