I use a claber reel fixed in the back of my pick up, I removed the top bar/handle and fixed the bottom bar to the universal channel in pick up bed using a sleeved tube and bracket so that it tilts forwards and lies on the open tailgate when in use then pivots backwards to allow you to close the tailgate reels in and out no problem I'm not sure of the total height but I could measure it tomorrow.
That's great ! Thank you very much.
I think my current reel is the Claber 40 which is very good indeed and holds 100m of microbore nicely.
There is shorter version called the Claber Aqua Pony which is the same design only angled back at about 30 degrees.
It looks ideal but 20m of 1/2 inch hose looks like your lot - 40 or 50 m of microbore probably.
I have a Mountain Top for my pickup which has an absolute height limit of 40 cm - current reel is about 46...