Welcome to the forum!
One option you may want to consider is becoming a foster volunteer. You can be upfront and tell the shelter/rescue that you would like a foster-to-adopt situation. In any event, fostering is a great way to get to know a dog. And, if it turns out not to be a good fit for your household, well, you are still helping the dog find the right home for him/her.
I should tell you that some rescues/shelters do not have formal "foster-to-adopt" programs. But, most will give the foster the first option to adopt if they decide that is what they want.