Doggy day care or day camp a few days a week. Or hire a pet sitter to come in for a few extra walks during the week.
Not wanting to sound harsh but... when you commit to an animal (particularly a rescue) you should really think about long term and keep that commitment if you can. It's very hard on the dogs to be rehomed multiple times
.
On the other hand, if you can find a loving home that you are sure will be long-term, ... more power to you. Please don't get anymore animals though until you are ready to commit to the full expected life....
My two cents.