That's why most vapes have some sort of extension piece or 14mm attachment for water pipes or J-hooks. I find that powerful vapes, butane vapes or desktops (like Underdog, Enano - through J-hook or water) are an important factor in reducing dry throat - simply because they are quicker to extract. The sooner you are done the less hot air you are sucking on. Another factor is your drawing technique. If it's too hot, let some cool air in through the sides of your mouth. You could also take a break or spread our your draws. And yes, have some water to drink nearby. With time your technique and vape choices will get better and you will be able to better protect yourself better against the wretched dry throat. But it's one of the hazards of vaping.