Cecil, W5DXP wrote:
"Is there anything in the design of a small loop that would prevent full
power plus foldback tuning"

Maybe off-resonance operation. The small loop is always inductive but
its reactance is high and its resistance is low, so it has a high-Q. It
has almost uniform current thoughout, so this produces nulls on its
axis.

Best regards, Richard Harrison, KB5WZI