Any clues how to achieve this without resorting to hardcoding the full URL instead of a project reference? (I want to use this link in a template DHE page so kind of hoping it can be done).
I thought about this point and I arrived at the conclusion that a project link cannot have a SSL protocol. This because when creating links to pages of the current project D.H.E. translates the link as relative so without the "http://" protocol before. This because a relative link is better and because D.H.E. doesn't know the name of your site when published on the internet and doesn't know where your page is within the site.
So for creating links in SSL mode act as you did before.
From what I can see, DHE uses a flat page model, so links between project pages are always at the same 'depth' within a deployed website created entirely within DHE.
Maybe you could add a Project level attribute for defining the fully qualified base URL for all SSL pages in this project then have an SSL checkbox or something on the Link Wizard option to Link to File in current project? Then DHE could create fully qualified https:// hyperlinks to SSL pages on generation and there would be no certificate issues either.
At least this way there would be only one place to hard-code the SSL base URL per project where there is a real mix of http and https pages? Just my 2c worth.[2 ??:-|]