This is yet another reason that despite having an F-350 in the driveway we bought a class C.
We can cover 600 - 750 miles a day on average without what I would describe as "pushing it".
On a trip from Toronto to Tampa (as an example) and by staggering start/stop times we can leave Toronto at 3pm on Day 1 and be in Tampa before midnight on Day 2.
We can take 2 weekends, and the week between, 9 days, and have 6 to 7 days in Florida.
If we were doing 300 miles a day, it would take 5 days to get there, 10 to get there and back.