Grant us the ability to choose what rank we play. Maybe with some limitations.
But other than that:
- playing a lower rank will not increase your current rank;
- winning any havoc mission of any difficulty will reroll your current assignment;
- losing a game of lower rank will not cost a deployment (same as now);
- assignment has to be attempted once before it can be rerolled or its rank changed.
Above are examples I thought of on the spot, so tweak as nessesary.