Just concentrating on the Less aspect;
Single engine Gosling.
Three engine FW Condor light.
Twin engine Lanc done.
U2 zero emission passive recconaisance glider.
Assymetric single engine Bf110.
Single boom, single engined fighter based on P38 parts.
Single engine Do 335 (front or rear - your choice).
Any car converted to horse drawn.
Mk IV tank converted to "prisoners in a treadmill" power.
Trireme Battleship (HMS Hood with three banks of oars for example).
Sloop rigged MTB.
Unpowered Boomer towed into action by a school of trained tuna...