First off, do you have a soft top? If so then you already have the 'door surrounds' (the something that can be added to close the gap) and those should make your jeep fairly water tight. I have a hard top and the bikini does leave a gap that allows water to get in. If you have a hard top like me you can purchase the door surrounds, but I think they are kind of pricey. Hope this helps.
So it's been, and shall be weighed: though many are born, few are "made". Faithful Always, they shall remain, dogs to loose when war is waged.