One possibility: Looks like SEA-TPA can be had as low as $203 plus "fees" RT. Expedia will display various 4 segment routes in each direction. You will need to play with the dates and times to get what you want. Possibly start with an over-nite SEA-MSP segment and then finish the other 7 segments during the rest of the day ending up on an evening MSP-SEA segment.