Would it not be better to use a darker primer paint where you are going to overpaint in a dark colour?
Maybe a grey primer, but this is not the case 
yes i suppose there are light and dark bits on this cab, and 1 primer is easier than 2.
its looking lovely in the mustard colour
are you a member of BYOAC? i have a thread there about paint codes and would like to add any information you have on the colour you chose to the thread, and wiki (eventually). if you can take a pic of the paint codes if you have them on the tin and post it if you are ok with me using the information.
