Declaring with a 200 or 300 run lead is not exactly aggressive or particular to a rain affected game. It's just relatively proactive.
I don't see the need to play the mind game. Who cares how many you think they can make? That's up to them. If it wasn't, you'd have them make 0. Just bowl them out and then worry about there being a target to chase. With such a good lead, it would be irrational to fear chasing for a short time. If they do get sunshine and manage to bat out of their skins, well and good, but setting a bigger total doesn't negate the effect of time. Either way there comes a level of performance that equates to batting out the game.
You don't find yourself ruing decisions so much if the other team does well. It's when they're 8 or 9 down and that's all she wrote, that's the point where self flagellation occurs.
I mean if the losing team manages to outperform the other in the last mile and catch up, then fair enough that there is merit in that. However, if you outperform them for pretty much the whole game and achieve nothing, what is the point?