Creaking in rear wheel
This type of cross gear configuration is frowned upon for normal riding. Mostly likely the creaking is caused by the extra stress caused by the chain putting stress on one side of the gears and chain. Lubing the chain and re-greasing the rear axle (if it is not sealed) could also help, as this creaking may be symptomatic that they are lacking. But the real take-away here is to avoid this type of gearing combination.