I would look into getting a new signal amplifier first, if I suspected bad reception, then move to the antenna.
my last Class C was built in 2008 and didn't do well with digital signals for TV. After the $80 amplifier was installed, i got double the stations without any further tweaking.
Winegard makes a big flat antenna that looks promising, but they are way more expensive than the amp.
Carl & Dawn
2015 Greyhawk 31FS
2015 Ford Transit Connect (our TOAD on a DEMCO Dolly)
DW, DSx2, DDx2 Catx2 Dog
Tampa Bay Area of FL