Dee Dee,
a piece of your analysis has to include whether you enjoy this type of thing. If it's arduous, then maybe it's not for you.
You also have to consider how you do your costing: if you are looking at your time based on what you make/hr. in your other job(s), then it won't make any economic sense.
I have some shows coming up in Miami December 7, 8 & 9; 2 All Breed shows and 9 Specialties. It's a 3.5 hr drive to Miami and 2 nights in a hotel plus meals. I'll set up my backdrop for Groups and change the backdrops for each day. I'll also shoot in the rings for the All Breed shows.
The Specialties will probably give me 6 - 8 images each to sell. The All Breed shows, because it's the end of the year and many Specials are retiring and won't need prints for advertising, will give me 100+- prints each. At roughly $25 per order it's pretty easy to see I won't make a lot of margin on these shows if I add in my "hourly wage". But if I look at myself as "free" labor that would be home mowing the lawn otherwise, then the cashflow starts to make sense. As long as I cover my out-of-pocket costs and still make some margin, it's worth it. Plus, I'll be showing my two old doddering Rottie Veterans in the Specialties so this will pay for their entries and handler's fees.
On the other hand, I enjoy shooting shows and I love the dogs. So to make a little money doing it is more than worth it. And it will buy some Xmas presents for the dogs (not to mention Linda).
I think your first question to answer is what type of shooting do you like to do. If the location stuff you do to feed your painting is what you really love to do, then forget about the studio stuff (except for Hallie of course

)
If this is a business question -- what type of shooting will give me the most payback -- then you have to look at whether your photography is a stand-alone product or just an adjunct to your painting business. And which one gives you the better payback for your time.
Can you make a living as a pet portraitist? Yes, but you have to build up tremendous marketing velocity to keep feeding it enough clients to be a good business. If you can build it up to a $60,000 or $70,000 per year gross income business, it can keep you and Hallie in Milk Bones. Otherwise, you'd better have a day job.
Just my opinions as usual.
Jim