Really torn about getting a 2nd dog!

We have a 1 1/2 year old Chessie/Shepherd/Kelpie mix who is 96 pounds and very energetic. We had originally said we'd hold off on considering a 2nd dog for about a year. We are hoping to have human children soon too. :)

The advice that I got from a wonderful trainer was to consider a young dog (but not a puppy), maybe a medium-sized energetic breed such as a cattle dog. She thinks a 2nd dog would be great for Wrigley, but a lot of work for me. I work from home and am usually alone for at least half of the week while my husband travels for work, so Wrigley is largely my responsibility. He is active with Wrigley during the weekend.

We found a Rhodesian ridgeback-lab mix who is 9 months old and currently in a kill shelter. I know it's not possible for me to save every homeless animal, but this dog stuck out to me as a great companion for Wrigley and for us. Obviously we'd meet him first, but once I meet him, I'll probably keep him...
Talk some sense into me, please!