Why not build a wire “Slim Jim” for 4m ? I used one of these many years ago and currently have a 6m one I built about 18 months ago that works extremely well.
It is constructed of “Open Wire” feeder spacers and mulistrand wire - on 4m it will be about 10 feet long.
Attach to the top of a short fishing pole so it hangs vertically, it requires no ground plane and should give you about 3dB of low angle signal gain.
It will roll up for transportation.
The sizes are available on various web pages or I can build one ( When the rain stops ! )