What you are saying is physically impossible....

First off - no legal CB radio produces more then 5 watts AM and 12 watts Peak Envelope Power ( PEP )..
Note I said 5 watts - back in the day of tubes, a brand new transceiver with brand new tubes would put out about 5 watts AM for maybe a couple of hours until the tubes broke in.
Once the tubes settled, about the best you could do - minus the peak n tune was about 4 watts.
Allowing a power factor - loss - this produced about a maximum of about 3 watts AM with mismatched components - since you wouldn't throw away all the tubes when one tube became weak or died.

Even with 3 watts and a VSWR of 1:1 - with a piece of coax 60' long to a beam antenna, you would have to deduct what the loss rate was of the coax before multiplying what ever the gain factor was of the beam antenna.

Hence you couldn't stick 3 watts in one end and have 3 watts come out the other end.

If PEP is 4 times the carrier, there is no way that you could get 10 watts AM and only 20 watts on SSB.... If it put out 10 AM it might show as much as 40 PEP on SSB depending upon the mode...

The carrier is a power hog, robs the transceiver of almost 60% of the produced power.
That leaves 40% to be divided between the two side bands.

60% of 10 = 6
40% of 10 = 4
Half of that would equal 2
4+2 = 6 watts minus the carrier..
Or a 50% increase in transmit power...