You have several problems running all at the same time. But, they can be solved.....
First off, since you are using a newt, you will want to consider moving to an OAG. This lessens the amount of stuff you have hanging off there. And, in the long run, you will want to do this anyway, since that arrangement you have will eventually drive you crazy. (Not for a while.....it will work. Just not what you want in the long run.)
Secondly, consider tube rings. These fasten to the dovetail, and allow the scope to move forward and backward. Shifting the weight, rotating, etc.
But, I am sure you did not want to be told to go out and spend more money......(Consider, though, that a set of rings, or counterweights, or whatever, may well cost nearly as much as an OAG! They can be had for not all that much. )
So, start by analyzing what you really need. You will want the center of your front-back load directly over your Dec axis. Where is the center of that load? To check this, take the (fully loaded, camera, guider, and all) tube and dovetail off the mount, and take a nice round piece of something (broomstick, length of pipe, whatever. big enough to work with, but does not have to be real large). Put that round thing on the floor, and put your dovetail on it, moving back and forth until the tube/dovetail assembly balances front and back. Note that while you are doing this, you will have to manage the front load from tipping over sideways without really adding or relieving any weight up there. When you find that balance point, mark it on the tube/dovetail with a piece of blue tape.
If you cannot find such a point (that is, it is in front of, or behind the dovetail, then things get a little trickier. You can:
....add weights to the light end. Never a good idea unless you have lots and lots of equipment capacity. And you do not.
....Move something further out. In your rig, the only thing that could move further out in front is the guide scope, etc Of course, the further out something is, the more moment of inertia you have to work against.
...Get a longer dovetail, long enough so that you can move the weight of the tube further forward or back relative to the dovetail.
...Remount the existing dovetail such that is it centered under the balance point of the front-back weights. (This is the best free solution.)
You have to do something along these lines first, or you will never be balanced front and back.
Now, lets move in that third axis.
The best solution is to go OAG, which puts the weight pretty much in line with the imaging camera, is lighter, and does not require as much setup each time you go out (and gives better guiding!). And then line that imaging train up with the counterweight bar. That is, you want to mount everything in one line. You can mount the guidescope opposite the focuser/imaging camera. This helps to minimize the inequality of the weight.
Next, you could mount them next to each other. This helps minimize inequality also. While you are at it, consider mounting the focuser pointing "downward" (in line with the couterweight bar--pointing towards the counterweights, not on the far side). This helps minimize the number of weights you have out on the counterweight bar, and the moment of inertia for the motor that has to push the whole thing around. BEWARE, though that this could put your rig in a position to crash into itself more, since the load on the bottom is extended toward the tripod, etc.
Okay, unless you have everything symmetrical, you need to balance in that third axis. That is difficult to do when your tube is actually screwed to the dovetail. You need to be able to rotate the tube. This requires rings to do it the right way, or weights, etc. Or redrilling and such.
To do it with rings, simply mount the tube in the rings, lock the dec axis, make the counterweight bar level with the ground, and move the weights as needed to balance. Lock the RA axis, and unlock the dec. Move the tube forward and backward until it balances. NOW....and here is the part that balances in the third axis....Point the tube so that it is vertical, with the dec axis unlocked. rotate the tube as needed until the load sits still. You should be able to now unlock the RA axis (the dec is already unlocked), and nothing will move. YOu are balanced in all three axis. Alas, you need to be able to both slide and rotate the tube to do this.
Alternatively, if you have a round tube, simply lie it on the ground. (or a table if you need to stick the camera and all off the end) and roll it around until it balances. Mark where it balances. This, along with the test you did to measure center of balance forward-backward, will give you an overall center. This is where you need to drill and mount your dovetail!!!.
If you can't do that, you may wish to consider weights......