Larger Breed To Be Trusted Around A Smaller Dog?

I’m considering rescuing a large breed dog once I leave the house. Kind of a security factor in the sense of large dogs are intimidating. I already have a papillon *very, very scary, no?* So the big dog needs to be compatible, at least when I’m around to supervise. They’ll both be crated when I’m not around.
I’m seriously considering a great dane rescue. if i were to bring one home while he/she was still young I’d assume they could be trained to “playnice.”
A lab is second choice, but I dont know how trustworthy it would b around Boo.
Is there any larger breed that would be “perfect?” Anything recently or currently bred for hunting is out.
Also, we’re out in the country and I’ll have a BIG fenced yard *chainlink, not chicken-wire* if that makes anything better. All animalswill sleep in the house, though.

Is It Too Dangerous To Keep A Large Dog With A Much Smaller Dog?

Right now, I have a two year old Papillon. But I love the Great Danes breed and have been wanting one for several years. In the near future, I may move to a place where I am able to have a Dane.
It would of course go through some training on not how to be rough with people (or dogs) but, aside from the fact that it may be odd or funny looking, is there any danger of keeping dogs of two drastically different sizes?