Shimano recommend a max of 3 mm clearance over the big ring. Is it possible to space the guard further out, to give the derailleur more sideways clearance ?
Raising the mech WILL cause shift problems. You can totally do it but the gate spacing will then be all whack.
I would want to look at the issue before giving a diagnosis.
I would imagine most bash guards would be designed for conventional bikes rather than recumbents.
You're right about them being the same Randall. Just move it up a bit and readjust, see how you go.
The manufacturers and repair websites all insist on a very close fit between the top of the chainring and the dr, however if you look at how bikes are set up by mechanics, the front dr is often/usually well above this. Soooo, my advice is to raise it and give it a go. If it doesn't work or causes other problems, then have a yarn with a mechanic who is versed in 'old school' ways - I've found some modern mechanics just follow the instructions and leave it at that where I've found others (such as Nathan at Tailwind) are able to fiddle and get things working properly.
Worth looking at this site every time your curious about something bike related.
Unfortunately Sheldon passed away before he got onto the modern hydraulic and suspension type stuff.