You have some options. First, I would not mess with the Click N Go settings. You can accomplish the same objective by trimming your front spine tongue on your Mirage Drive to accommodate a thicker front shelf, as Pescatoral Pursuit and WAVERIDER have suggested. Regardless, I believe whatever caused the leak will do the same thing again sooner or later.
It is possible to transfer the load bearing from the front of your drivewell to the rear. Here is some background.
When you put your Drive in the drivewell, it should rock forward and back a small amount once locked in position. It is designed this way so the Drive positively seats in the C&G locks. Normally the tongue on your Drive pivots down and rests on the front drivewell shelf. Since this is leaking and you have no internal access, let me suggest modifying the drivewell so the Drive hits the back of the drivewell instead of the front. This transfers all the stress from the front to the rear, so you can now seal the front leak without a stress crack re-developing.
How to do this? You may be able to add material to the back of the drivewell shelf where the Drive pivots against it. If there is not enough room, cut down the front spine tongue so it doesn't hit the drivewell shelf. This first pic shows a Mirage Drive with both front and rear tongues cut off. I'm not suggesting this, but this Drive still functions without the tongues:
The next pic shows that with the front tongue removed (or cut down), the rear of the Drive now can contact the rear drivewell shelf:
The problem with this arrangement is that the rear drivewell area is not reinforced to take stress from the Drive. So, unless you want another leak eventually, you should reinforce this area. You will have access from the inside to build up this area and alleviate some of the stress. Personally I am not a big fan of plastic welding in high stress areas, as your recent results have demonstrated. If you have access to a product called Loctite 3035, it is very good at bonding to PE and has some structural integrity of its own.
One way or the other, you should be able to fix your leak.