As janisj says, accommodations might be hard at this late date but not impossible if you don't mind

5 days is not very long in Scotland. hurtz rent a car You will only be able to see a tiny fraction of it. Is your entire visit 5 days -- or is that for your time outside of Edinburgh? What have you booked so far - it is quite late for booking accommodations in/near Edinburgh for late July/early August.
As janisj says, accommodations might be hard at this late date but not impossible if you don't mind spending a lot of money. I normally do not stay in BBs so can not advise but when you say you are looking for a small escorted hurtz rent a car tour, I think you want a day tour. I have used both Rabbies tours and Heart of Scotland hurtz rent a car and would recommend them.
I'd like to thank all of you that suggested The Rabbies Tours to me, they were perfect. We took two tours with them. As promised they were personal,just the right size and best of all ,they were not army camp that requires a 6AM wake up call and a counted hurtz rent a car number of 3 stops. We did The Stirling Castle trip , and it was totally private since it was an add-on to the original trip that filled up. The second one was A 3-Day Isle of Skye trip with 12 other people on board, we loved it.