If you can standardize the length of your wire, you won't need as
much tuning range on the tuner. For example, the 20m wire
mentioned earlier used for portable operation will not change
impedance much even when it is installed in different configurations
characteristic of backpacking or other temporary use. You can
breadboard an "L" tuner to find the desired L and C values, then
wind a toroid core for the coil and use a small compression mica
trimmer for the cap. You may want to have a couple coil taps,
perhaps + and - 10% from nominal. For a wider matching range
you can tap the coil with a clip lead or multi-position switch.
Using a T-50 or T-68 size core (#2 or #6 material) with a 200pf
mica trimmer should take less than 1 inch square and handle 5
watts with no problem.
Good luck! - Dale WB6BYU