TL;DR: Use one wolf for mining, a different one for fishing, and a different one for campaign (and only one). Rodill are good on mining & fishing wolves for stamina regen. Give Biggs & Tiny their payment so you don't have to babysit your crops, and always have your plots going as much as you can. Fish whenever the activity shows up in the activities bar. Cook everything & always have your cooking pot full. Manual feed will allow you better control over which of your foods your wolves will eat and help you maintain a good balance.
Give Biggs & Tiny their payment, and you don't have to maintain your crops. Once you max Rice seed familiarity, you can average 30+ Rice per plot, every thirty minutes. You can get more if you maintain your crops yourself, I think, but I feel the trade-off is more than worth it. Plus, you can clear that task from your activities bar.
Fishing is also helpful. It takes up 25 energy for each trip, but you only need 2 trips to clear that from your activities bar, even with the first area. I usually only fish if it's on my activities bar anyway, or if I need to replenish my cooking stock. That way, my wolf has a chance to regain their stamina. Giving them a Rodill companion helps, as they will replenish stamina when played with (up to 50 at level 10).
Cooking is probably one of the better things to do. Cooking fish takes them from replenishing 5 stamina to 20 stamina, and fish cook fairly quickly. The higher your cooking level, the faster you can cook and the less likely it is that you'll burn anything. After a certain point, you won't burn anything at all, no matter how complex the recipe. If my cooking stock is low (no fish or even cooked meat), I'll stock up on Pumpkin Pies & Crunchy Rainbow Bug Soup for Biggs & Tiny. That way, I always have some on hand for when I need to pay them to maintain my crops.
My favorite areas to grind are the second area in Darkspine, the third area in Icerun, and the fourth area in Goldsea.
The second area in Darkspine is fairly easy to tackle with even a single level 1 wolf and their level 1 companion, and is a great place to start levelling both. It's also one of the better places to get ingredients for cooking Crunchy Rainbow Bug Soup for Biggs & Tiny. The Folium drop two of the ingredients needed for the soup. And (as has been mentioned) the Grimalkin drop fish. You can also pick up plenty of snails from those scenarios.
The third area in Icerun is great once your wolf and companion are ready to take on the Lapistrix. I find the Lapistrix easier to tackle than other third area mobs, and they drop fish as well. They're also good for getting trinkets, which you can then sell to the vendor to make additional pebbles. Isopod encounters seem to have been moved to third areas in the campaign, which also help you maintain stamina - especially as isopods come in 5, 10, and even 15 stamina regen flavors.
The fourth area in Goldsea is my favorite to grind in, once my wolf and companion can take on the Broch. The boss encounter doesn't happen with enough frequency to deter me, so I don't worry about not being able to solo it. The fish I get from the Broch & fishing that I cook as well as the moths are able to keep me going. I get plenty of trinkets I can sell to the vendor, and wild wolf encounters aren't terrible.
I use one wolf for mining, one for fishing, and one for campaigning. If you equip a Rodill on the mining and fishing wolf, you can decrease the amount of food you need to feed them, as once per hour you can play with the Rodill to replenish stamina. Feeding these three wolves individually can also help you maintain your food stores. I personally like to do 2-3 stamina regen foods of different types (ex - 1 cooked Koi, 1 cooked Salmon, 1 cooked Meat), and the rest in Corn or Rice. My Goldsea grinding wolf will get 4-5 moths and 1 each of a cooked food, and a single Corn or Rice if I still need something.