If you are willing to ride all interstate, the trip should be doable. You should be able to average 50 mph if you stick to all interstate, avoid cities during rush hours, and limit yourself to reasonable stops. I would do a 16 hour day on day one as you should be rested at the start of the trip. That should put you around Oaklahoma City. I would shoot for Indianapolis on day two which should take about 12.5 hours. If you still feel good in Indy you can always keep going. That should put you about 11 to 12 hours outside of Philly. The amount of distance you want to cover in the time you have allotted is doable, but will be uncomfortable. I have done some over ambitious trips, and for me the most important thing is to keep well rested.