I'm glad to hear that Tortilla has figured out how to get in, but I see a couple of problems looming on your horizon. I learned these things the hard way and hope that by sharing my experience, you won't have to learn the hard way too.
1. You need a door. Best if it is insulated like the rest of the box. They will go in their box and stay in there all night every single day for months, and then for no apparent reason, you will find them nestled in a corner outside some morning after a cold night. Who knows why they do this, but eventually they do it. Lock the tortoise in after dark or at dusk, and then open the door each morning. This also keeps rodents, raccoons and other tortoises predators away from your tortoise.
2. CHE's are NOT the way to heat an outdoor tortoise house. The don't heat the whole box and floor up enough and they concentrate too much heat into too small of an area. I've seen this over and over. Please take my word for it before this happens:
http://www.tortoiseforum.org/threads/open-topped-pyramided-scute.19691/#post-174030
Here are two examples of better ways to heat your tortoises night box:
http://www.tortoiseforum.org/threads/another-night-box-thread.88966/
http://www.tortoiseforum.org/threads/my-best-night-box-design-yet.66867/
Also: 75 degrees over night is pretty border line unless you are consistently having sunny days in the 80s or higher every day. I'd bump that up a little until we get to summer.
1. You need a door. Best if it is insulated like the rest of the box. They will go in their box and stay in there all night every single day for months, and then for no apparent reason, you will find them nestled in a corner outside some morning after a cold night. Who knows why they do this, but eventually they do it. Lock the tortoise in after dark or at dusk, and then open the door each morning. This also keeps rodents, raccoons and other tortoises predators away from your tortoise.
2. CHE's are NOT the way to heat an outdoor tortoise house. The don't heat the whole box and floor up enough and they concentrate too much heat into too small of an area. I've seen this over and over. Please take my word for it before this happens:
http://www.tortoiseforum.org/threads/open-topped-pyramided-scute.19691/#post-174030
Here are two examples of better ways to heat your tortoises night box:
http://www.tortoiseforum.org/threads/another-night-box-thread.88966/
http://www.tortoiseforum.org/threads/my-best-night-box-design-yet.66867/
Also: 75 degrees over night is pretty border line unless you are consistently having sunny days in the 80s or higher every day. I'd bump that up a little until we get to summer.