DD, I'm not sure if I have the answer you are looking for, but I'll take a stab at what I THINK may result. I'm still not sure what your end goal is. Are you looking for increased durability? Just looking to raise ride height? Anyway, I'll do my best and hopefully others will add their expertise along the way.
Putting a rear on the front, from a durability standpoint, will probably make no difference or a negligible one at best. Rear shock towers are not made any tougher than fronts, they're just taller (at least in most cases). If the end result you are looking for is increased ride height, you really don't need to change the shock towers, you need to change the dogbones to your wheels, the tie rods (turnbuckles) and the steering rods. Think about it, if you take your shocks off and raise your rig by the chassis only, at some point the A-arms are going to drop only as far as the tie and steering rods allow it to. If you unhook those, at some point the arms will drop far enough that the dogbones will come out of the diff outdrives, right? So, theoritically, if you want to raise your rig, you need to change out more than just the shocks and you really wouldn't need to change your shock tower.
One other thing to keep in mind, as you raise your rig, your center of gravity rises as well, meaning it will be more inclined to tip over than before. If you want to raise your rig AND keep the handling par to how it is now, you'll need to widen it as well, which means new A-arms all around.
If what you want to do is strengthen the rig to handle a bit more bashing, what I suggest is looking into some slightly taller buggy shocks (like rear ones) and some wider rims and tires all around. It'll raise the height a bit, but not so much that it rolls on a whim and buggy shocks are typically a bit more durable than the stockers on a 1/10th rig.
You may also want to consider adding RPM bumpers and A-arms at some point, which will make it virtually indestructable.
Adding a rear shock tower won't hurt it any, but I doubt it'll give you what you're looking for.
Hopefully I've helped, at least some. Good luck!
