Mark Keith wrote:
"Start with a center load. Note the current taper. Then place the coil
below the midpoint level. Note the current taper."

Mark may want an indication of the better site on a too-short whip for a
loading coil. John Devoldere, ON4UN shows what he`s found in his book
"Low-Band DXing". On page 9-14 John says:
"It is clear now that the real issue with short verticals are EFFICIENCY
and BANDWIDTH. -----Therefore maximum attention must be paid to these
terms by:
Keeping the radiation resistance as high as possible
Keeping the losses of the loading devices as low as possible"

John gives radiation resistance formulas for base loading, top loading,
center loading, combined top and base loading, and linear loading.

John says on page 9-19:
"The rule for keeping the radiation resistance high is simple:
Use as long a vertical as possible (up to 90-degrees)
Use top loading

Low-Band DXing is worth checking out.

Best regards, Richard Harrison, KB5WZI