We have a larger dog (also named Rusty) who is mostly the outside guard dog, but he is inside in bad weather (hot, cold, rainy) and sleeps inside at night.
We got him as an adult rescue and he has never been housetrained, but sleeps happily in his crate at night. During the day, he is in and out, whichever he prefers, and each time he comes in, he runs into his crate, and then I give him a Milkbone dog treat to enjoy.
Poodle, on the other hand, is housetrained, and sleeps next to me in bed at night. He is also in and out during the day, and gets a biscuit when he comes inside the door. (Yes, both dogs want to go out and then come back in, just to get that dog biscuit, totally spoiled)
Poodle is older and sometimes has bathroom issues at night, so I got him one of those doggy bands to wear to bed, and that works perfectly.
If he fusses at night, then I get up (take off Poodle’s band) and let him/Rusty outside; or if he just has an accident in the house, the band takes care of it, and can go right in with the other laundry.
As a special treat at bedtime, after the last trip outside to potty, both dogs get a little bit of a hot dog or bologna, so Rusty always dashes into his crate as fast as possible.
He is happy in there, and stays inside his crate, even if we forget to close the door.
I think that if your Rusty does not like sleeping in the crate, and is out of it during the day, that just a band at night might solve everything for you as well,
@Nathan . You can leave the door open to his crate and see where he decides to sleep.