Salti, the principle is pretty simple. You want an extension of your front roof rack so you can rest the kayak against the side of the car and the extension bar, then lift the rear and swing it around onto the rear rack. Conversely for unloading.
So you just need an extension that is secure, able to take the load (approx the weight of the yak), and is convenient to deploy and remove.
PeterJ made one that you will find by searching the forum.
I bought one that clamps onto the front rack using four bolts. It has a foam covered bar that sits alongside the roofrack when not deployed. It pivots inside the clamp to swing around 180 degrees, thereby providing the extension. A springloaded button on the bar near the pivot point and matching holes in the clamp secures the bar in either the rest or deployed position.
So you just need an extension that is secure, able to take the load (approx the weight of the yak), and is convenient to deploy and remove.
PeterJ made one that you will find by searching the forum.
I bought one that clamps onto the front rack using four bolts. It has a foam covered bar that sits alongside the roofrack when not deployed. It pivots inside the clamp to swing around 180 degrees, thereby providing the extension. A springloaded button on the bar near the pivot point and matching holes in the clamp secures the bar in either the rest or deployed position.