Jerry, I would be careful about plugging a longwire in directly.
Apart from overloading the receiver, there is much greater risk
of a static surge damaging it, possibly terminally. Feeding
the longwire signal via a tuner, trap, variable attenuator,
reverse-diodes, gas-discharge-tube, varistor etc,
as suggested in posts here, would, however, give you
reasonable protection - except from a close lightening strike!

The simplest approach is the one you are using : loose
coupling of the incoming longwire to the telescopic aerial.
You could try feeding an external ferrite tuned L/C
from the longwire. The ferrite and tuning capacitor from an
old AM radio would be suitable. Varying the distance to the
G3 will allow you to optimise the inductive coupling without risk
to the G3.


Longwire --------------
I
------- --------------
I I I I
L C gap I G3 I
I I I Receiver I
------ ---------------
I
Earth


Hope this helps!
Michael UK