Mackerel is a good fish to smoke and I know what you mean about the golden hue
It is possible that the lack of colour was due to the smoke passing more quickly through the smoker with the vents open. Were you using the same smoking wood as before?
Before you try to smoke them further I would again suggest that you try one and see if it already has picked up sufficient smoke flavour.
Next time you smoke them you may want to smoke them in stages as this will help form up the protein slowly in the fish. A good method I have found works well for mackerel is
Gut the mackerel and remove the blood channel that runs along the backbone. Wash the fish well under cold running water. You can now lightly score the skin across each side if you want to let more smoke into the meat. I don't usually score mine.
Immerse in a 70%-80% brine (250 g non iodised salt per litre of water) for 1.5 hours if un-scored or 1 hour if scored. Again rinse under cold running water to remove the surface brine. This helps to firm up the fish.
Hook the fish through both eyes (or use a skewer) and then hang in the smoker. Place little pieces of wood between the belly flaps to keep them open - cocktail sticks are great for this.
Smoke at ~45 C (115 F) for 30 minutes. Then then raise the temperature up to 80 C (175 F) for 1.5 -2 hours depending on the size of the fish. The skin should turn a deep golden colour and become slightly wrinkled.
Allow to cool and then wrap.
If you are smoking them filleted then only brine them for about 45 minutes.
