There is no known qrp tuner for both small magnetic loops and longwire antennas for sale so here is an idea for your next holiday . A 2.5 m circumflex loop wil cover 6.5 - 30 MHz , a 5m loop wil cover 3.4 - 8 MHz. To tune a loop tune C1 for resonance and C2 for low swr . To tune a longwire switch to the coil for the desired band and tune C1B for best swr. The coil can be replaced by a T130-2 toroid with 50 turns 0.8mm enamelled wire on a 12 positions rotary switch. Use a plastic cabinet for this tuner.
Tuning capacitors :http://www.rfparts.com/old_site/caps_antennaload.html
Tuning capacitors :http://www.rfparts.com/old_site/caps_antennaload.html