it looks like that method just extends the tube so you have less copmression and more extension so you are less likely to have it fall apart. The fact of the matter is that toyota front drivelines just do not have enough slip built into them to handle a good flexy suspension. You need to have longer splines. Thats the only thing that will fix your problem. So your options are basically to build a square driveshaft or use a long spline kit. There are plenty of write-ups on this forum that will tell you how to build a square shaft, just use the search function. Pro's of a square shaft are: it will never come apart again, fairly cheap to build. Cons of square shaft: cannot be balanced, square tube will never fit as tightly together as splines do so it will have some slop, If you try to drive it in 4 wheel drive during anything but crawling it will bang around and shake pretty bad. Long spline kit is the best way to go if you can afford it. Pro's: plenty of slip and will never come apart, splines fit nicely together so you dont get the loose banging and wobbling effect, it can also be balanced fairly well. Con's: it cost 200 bucks shipped to your door, then you still have to pay a driveshaft shop to cut your old one apart and weld your CV joint onto the new long spline shaft.
You also said that you dont have enough room to use a long slip shaft. thats kinda weird because i have had one on both my rigs without dual cases. Also marlin sells an 8" slip unit that should fit in the space you have. And i think all-pro sells a 10" unit, so you do have some choices if space is limited.
Got any really clear pics of your front shaft with it compressed and drooped? Specs of the actual angles and length too? I installed All Pro 5" and I have the same problem as dweinberg01. That would help a lot. Thanks a bunch guy!!!!