Peter, VK3YSF wrote:
"Or is there simply a better way?"

The 0.7 mtr wavelength is an advantage. The separation between antennas
only needs to be a few mtrs to be "far field".

The tested antenna can be side by side and tip to tip with a reference
antenna, dipole or otherwise, of known gain, and the interaction should
be small. The antennas will be in each other`s nulls.

Reception or transmission from the tested and reference antennas may be
compared as reciprocity rules.

Of course, the same power or field strength must apply to the tested and
reference antennas for validity. Losses in associated systems must be
the same for the tested and reference antennas or any differences must
be accounted for.

Ther antenna sitings likely won`t correspond to free-space, so a
reference of 0 dBd or its equivalent of +2.2 dBi won`t be precise, but
the comparison between the "known" reference and tested antenna should
be valid if the antennas are operated in similar circumstances.

It isn`t necessary to build a field strength meter if a receiver with a
good signal strength indicator is available and a calibrated generator
is available. The off the air signal can be replaced with a signal from
the generator and its strength can be read from the generator`s
attenuator. I`ve done it countless times and it works well.

Best regards, Richard Harrison, KB5WZI