The ministry of transport does not set tow ratings. The vehicle manufacturer does. Check your vehicle's owners manual for them. These are different than the receiver limit as well, which may be higher or lower than the vehicle tow rating.
2009+ GM half tons (Avalanche, Burb, Tahoe, Silverado) have GU4 or GU6 (3.08 or 3.42) with the 6-spd trans. Tow ratings for the 5.3L are all under 10k.
Anyway, practically, 5k dry is a reasonable safe limit for RVing. THat will be more like 6k loaded for a long weekend with 700-900 pounds of TW. That is enough weight for the -08 4-spds for acceleration and power, and the 09+ for suspension.
