Changing the timetable for the sake of a longer sleep is very unlikely, not many places on the WCML to have a lie over enroute, platform space at Waverley means a long lie there is not going to happen, north of Edinburgh times impact with the first day trains, southbound it's unlikely that a stopover is viable either.
What proposals could you suggest for these passengers that are more interested in a long lie than getting there?
Advertised times to vacate berths are also not achievable on the Lowlander at Waverley, so to prevent complaints these times should be changed to what is achievable.
The only places I can think of from the top of my head regarding the places where there could be a layover (assuming present day route via ex Trent Valley Railway) at a stretch would be Warrington Bank Quay (can easily pull over to one side, but unlikely as Preston back northbound is not too far away), Stafford (there are already through lines there), Rugeley TV to Nuneaton inclusive (this section is quad track), Northampton (unsure if trains from the depot can pass a train that is in the London platform - I think the northbound platforms are an island), and maybe as a last resort Milton Keynes Central (there are six platforms, and I believe overtaking moves are allowed). This comes with the caveat that I have not looked at the Sectional Appendix, nor have I had a look at the Real Time Trains website to get an feeling for how much traffic there is at those hours of the day.
All in all, my view is that the Caledonian Sleeper would most likely be post-HS2 for any major revisions to service. I have mentioned a long time ago (unsure if this thread or another one) that the Highlander section be revised to run to Inverness and Fort William as one portion running via Birmingham, with the respective portions uncoupling/coupling at Mossend Yard. Inverness portion would continue via the ex Caledonian calling Coatbridge Central, Cumbernauld (Carbrain - suffix appended if the proposed station near Abronhill opens, no change of three letter code CUB), Larbert (compensate for Falkirk Grahamston, as Larbert is a couple of miles round the corner), Stirling, then as existing present day calls. The Fort William portion would then call Coatbridge Central, Glasgow Queen Street low level* Westerton*, Dalmuir, then as present day calls.
*As there are a myriad of routes from Mossend Yard, alternatives on the way to Dalmuir during engineering works could be Springburn (interchange with Queen Street via Bellgrove or direct via Cowlairs), then Western and as above, or via Glasgow Central high level, then via the ex Rutherglen & Coatbridge via the top side of the right pointing triangle at Langloan Junction, then either Queen Street low level or Springburn to Western, then as normal. Also, if the stock fits the tunnels, there is Central low level, then onwards to Westerton/Dalmuir.