Can you explain how you are looking at getting it done so that you do have access to everything? I have a very nicely done en suite which is tiled all over. I also always wondered about access if ever there was an issue. I think it would literally also have to be a rip the tiles out job.
Yes using one of these: https://www.youtube.com/watch?v=FzRLl0j5wCU
Anything serviceable is accessed through the front panel. Some of the pipework is still concealed but the frame holds it all in place so it's firmly pushed in to the toilet and doesn't move around. You use them in conjunction with a wall hung toilet.
The smallest 0.82m frames are around £150 so pretty reasonable. Seems like a good solution to me.