You can experiment with different antenna height and location using the
Interactive TV Maps tool. Adjust the antenna height, looking for a NM figure of -5 dB or better. (An antenna with 15 dB of gain would theoretically add to the -5 dB NM, yielding a net NM of +10... enough to hope for fairly reliable viewing.)
That still leaves you with the problem of adjacent and co-channel interference and as TB pointed out, strong locals.
If this is a system specifically aimed at DX reception, intermittent reception may be the norm for the very weak or interfered signals. Wade is a commercial grade antenna source, Blonder Tongue is another. The Wade
Parabolic is an extreme example of high gain antenna... If you are determined to see weak signals like WTAE... you will need a big tower and a big antenna.