The Dawnstrider Army is nearly 3,000 strong, but very few of it is mobile. Each city has a standing garrison as large as can be comfortably housed (at least a good hundred in the smallest hamlets, up to several hundred in larger cities), with about 1,000 serving as the mobile army that polices the borders and handles reinforcing cities in peril. The Dawnstriders could never mobilize the entirety of its soldiers for battle, because that would involve taking literally EVERY soldier in the various towns, leaving every city completely defenseless and lawless, since Dawnstrider soldiers double as local law enforcement (to say nothing of the catastrophe of trying to manage a such a tremendous supply train with no soldiers to organize or defend it). In reality, it would strain the Dawnstrider Protectorate greatly to field even 2,000 soldiers. A thousand men is already considered a great investment, and typically 500 or so move about the various patrol paths while the other 500 are kept on continuous duty, moving from city to city helping with projects or escorting trade caravans to neighboring nations or down to Barak Varr. The Dawnstriders make the majority of their wealth selling barley and wheat to the dwarfs to be brewed into beer, and spend the wealth importing more food and gear for the army.
This is how Arathos manages to feed and pay his men; outside of battle they perform public works, everything from helping till fields, to paving roads and building walls and towers. Although they all recieve periodic training and maintained equipment, and despite the fact they are full time, paid professional soldiers, they are in many ways no different than militia that answer a call to arms. During their downtime they live and work among the peasants under their care (often in their hometown), the only difference being their armor and weaponry. The additional wealth and food comes from seeking out and destroying bandit hideouts, goblin and orc tribes, and skaven tunnels, and plundering their supplies for salvageable food to feed the men. Anything metal is sold to the dwarfs as scrap (if they'll take it), or smelted into gear to be sold to the villagers under the Dawnstriders' care (if the dwarfs won't). Obviously, the extra wealth they come by depends largely on finding and destroying said enemies, so Arathos commonly spends the summers and early autumn leading expeditions into the mountains to the east, where orc tribes are plentiful and loot can be brought back in decent numbers.