I see this is your first post. Welcome to the Air Forum!
There should be an air bubble, a cushion for expansion, inside of the water heater. This is normal. Do not activate the pressure relief valve or the WH will loose this bubble. Then the pressure relief valve might start dripping to relieve expansion when water is heated.
Aeration happens at the faucet, not in the water heater. You might unscrew the aerator and clean it if flow is reduced.
Have you flushed the water heater, prior to turning on the faucet? This is maintenance you should be performing (see the water heater pamphlet that came with the trailer )
If hot water flow is reduced and if your trailer has a water tempering/mixing valve that is another thing that has a screen that captures particles when the water heater is not maintained properly. If this gets stopped up, it requires removal and repairing the mixing valve.
2014 Silverado LTZ 1500 Crew Cab 5.3L maximum trailering package