If you used the second run that is free I think we can safely discount any grouping factor. The only circuits to consider would be the rear demist and the wiper, all others are negligible loads or intermittent/short time loads. I think we can ignore those if you keep your cable separate. 6mm is the minimum size really. You are unlikely to run thecair compressor for 30 minutes or more so this can be discounted for loading.
As Moggy said the accessory sockets can be a concern, Best avoid these or fuse them down appropriately. In other words hard wire the compressor or use a dedicated plug. Cigar lighter sockets are awful things for anything more than a few amps as they can get hot and melt over time. Hence also aim to hard wire your fridge in. Consider using Anderson connectors of 20A or more for disconnecting if you really need to. No reason to avoid cigar lighter sockets for occasional use of chargers etc though but keep fusing to 7 to 10A.
6mm, in the unused Channel will in all practicality be perfectly adequate for your current and future planned loads as listed.
As Moggy said the accessory sockets can be a concern, Best avoid these or fuse them down appropriately. In other words hard wire the compressor or use a dedicated plug. Cigar lighter sockets are awful things for anything more than a few amps as they can get hot and melt over time. Hence also aim to hard wire your fridge in. Consider using Anderson connectors of 20A or more for disconnecting if you really need to. No reason to avoid cigar lighter sockets for occasional use of chargers etc though but keep fusing to 7 to 10A.
6mm, in the unused Channel will in all practicality be perfectly adequate for your current and future planned loads as listed.