When i was out of town, per diem was $20/day and lodging was paid for. That was almost a decade ago. Was below avg but breakfast was free, cigs were $2.50 a pack, and you could find a lunch for $3 and dinner for $6. We had money left over most days, enough so that we could go to Longhorn for steaks and drinks at least twice/trip, and a bbq joint or two as well. VA, NC, SC. We stayed in everything from HIE to places that made the Bates Motel look like a HIE.
We did have problems twice with lodging not being pre-arranged, but we sorted that rather quickly.
eta: food isnt your only expense. Oddly enough, laundry came in second behind food, especially in the summer months.