This is probably one of the most legit thread and question on the CX forum lately beside DMs whining about this and that, or newbies starting new threads for some of the most commonly asked questions. Please do report back if you decide to make a call to MPO and ask, it will be a great data point.

If all else failed, what you can do is not book your April longhaul ticket with your MPO status first. You won't miss out on much, if any from your GR status. Then exactly 6 months later, file for a missing mileage. Unless your first trip was taken on April 1st....6 months later, you would already be passed your Oct 1 reset. Only risk is, it might be kind of tight...