If you "really are" going to stay with shorter logs, and you want to make full width slabs, you have no choise but to get a BIG powerhead and a long bar, and live with all the back breaking work it takes to run it.
I disagree that using a CSM needs to be a back breaking activity. The reason that most people find it back breaking is because they approach it with twenty year old bull at a gate enthusiasm instead of looking at ways of minimising the effort required.
To start with I never carry my mill any distance because of these.
I can even wheel it through the bush if it's not too dense.
On site the mill is lifted onto a table (mill weight 72 Lb so it's 3 seconds of back breaking time) usually set up right next to the log
Here I can refuel/re-oil and service it standing up
To sharpen it I lay the mill over like this
I even bring a plastic chair with me to the site so I can sharpen sitting down.
Log gets lifted with this;
Then it's a 3 second lift to get the mill onto the log rails to this position.
Start engine on rails and if the chain is sharpened properly and the log is on a slope the operator should just have to lean on the to make it cut. This is no different to BSM.
When I'm really lazy I leave the wheels on the mill and wheel it back to the other end of the log but usually I carry it (7 seconds? of back breaking effort).
Now the slab has to be moved but this is an issue whether one is using a CSM or BSM. This is where the Sack Trolley or hand truck comes in handy.
I agree it's a very slow process but one thing it definitely isn't is back breaking. I'm an overweight lazy (and to use an Aussie colloquialism) parent-less offspring, if it was back breaking I wouldn't be doing it.