I did replace my rack and pinion steering last year that lasted over 23 years without removing the motor. Every marina told me the motor must come off. I did it with some help by a knowledgeable pal. It was tough trying to make a 90 degree turn but by removing the carpet and making the hole bigger on the starboard side panel we did it. Carpeting covers much aluminum surgery. The old shaft would not come out, and because it was longer than the clearance without cutting it in 6" sections I would never get it out. I needed to soak it in anti seize (not WD 40) put a pipe wrench on it and tap it out with a hammer otherwise it would never come out.
A tip if you do DIY it, clean the sleeve that takes the shaft super clean clean. There was 23 years of old grease in there. There is also a fitting that you can buy for the new cable that makes it grease able at the rack if your new cable isn't. I didn't put one on because the steering now feels like it's fully hydraulic compared to before and didn't know they existed other wise I would have, I still can I believe. One finger steering now. I doubt I will outlive the new cable. A fishing partner upgraded to hydraulic on his boat and is disappointed after many $$ when he felt my steering, it is smoother than the hydraulic assist he bought.
Another tip is to use bolt cutters and cut the cable out in sections rather than pull the entire cable. And yes tie a good line to the last section of cable to help feed the new one. I also ran the new cable through a long section of ABS to help the next guy if there is one. If I ever need to run a new electrical cable from the helm I will run it through that piece of ABS. Then all I need to snake that wire through is use a good shop vac and suck the fish line through. A great trick I learned from a plumber when I ran a inline heat trace cable on a 35 foot water line for my water system to a cistern. He tied some tissue paper on the end of the fish line, great trick.
