Actually, if only focusing on one toon, the math works out like this (assuming that my information is correct):

Assume you do enough in one day to get enough marks for original projects, and then some (for both Omega and Romulan). This is not hard, especially if you turn in the missions on Romulus during the Marks hours.

Assume that is one full day of play, averaged out to 8hrs, though I did it in much less. Original Projects are 1d16hr. Assume also you have the credits to buy enough items to finish out the rest of the projects requirements. The time to 2800 xp for both is now 2d even. That means 4 days to complete the requirements, plus 1 day to upgrade. So call it 5d minimum, maybe 5d12h if the timing doesn't work out properly.

Now if you are splitting time between toons to do them simultaneously, the numbers go up, but it is still doable if prioritized properly.