TPA-IAD looks like it could be a tough commute.
There are only 3 available flights, but luckily they are on your mainline partner. However you have plenty of senior mainline people who commute on the route.
As an example today flight #1 is showing only 2 seats available with 7 people competing for them, #2 is showing -1 seats available with 4 people trying to get on. And #3 is showing -8 seats with 3 people trying to get on.
I make the MCO-IAD run and we normally have 4 direct flights a day, (3 in the low season). It would be difficult commuting had I not had the option to get on Jetblue going to DCA.
Speaking of which, there are 7 flights TPA-DCA on other carriers.
So it might be doable after all...