Topband: inverted L question

[k1my]

I am working on plans to put up an inverted L for 160 and have a few very
basic questions.

The L will be 100 feet vertical and about 100 feet horizontal or so.

1. Is longer than 100 feet horizontal better?

2. I understand that I need to add capacitance, some have suggested a vacuum
variable at the base. I just finished reading the Feb 03 QST evaluation of
antenna tuners. Will an antenna tuner in the shack accomplish the same as a
box at the base of the tower and am I reading the "product review" correctly
that they Ameritron ATR-30 is the best of the lot for this purpose?

Thanks in advance.

73, Bruce K1MY/7