The tilt really isnt a pain, and isnt usually very usefull UNLESS you also have the offset feature. The tilt, tilts ALOT. Only really good for digging a shallow trench WITHOUT the offset feature.
So...if you are ditching without the offset, you dont need much tilt, in which case using the 3PH linkage isnt bad at all. The idea of tilt and offset working TOGETHER is you can stay up on the flat and do ditches. Since without the offset, you will have to drive down in the ditch, the tractor itself "tilts"
As to strengthening....usually the blade itself is the weak point. The pin on the blade you are looking at "could" have been repaired just because of years of use...it got sloppy. Most of the time I see a blade bent or tweaked, it is the blade itself bent. In the picture you posted of that 2184, notice the extra roll at the top, and then down by the cutting edge, the peice of steel welded on edge. If you can imagine sitting behind your blade, with your feet in the middle and grab ahold of each end and pull backwards, (like a bow and arrow), it is easy to see how that simple little peice offers alot of re-inforcement.
Take a look of the backsides of blades like these for ideas
RBT35 Series Rear Blades | Land Pride
http://www.kingkutter.com/store.aspx?id=137
RHINO | Blades | Heavy Duty Rear Blades
Notice they are all rely on more than just the curve of the blade to keep it from turning into a reverse u shape. Some use flat steel and gussets, some use a box-it-in approach. Not hard to get creative and come up with somehting effective.
I can say for SURE, since I have never looked at a 45 in person, but I would think that the 3ph a-frame and king pin would hold up fine.