I agree that dry mounting would be the way to go. Can one dry mount directly to aluminum or would you need to dry mount to rag board and then mount that to aluminum?
Forget mounting with rice or wheat paste for something this big. I don't EVER want it coming up. The idea of removing a large print safely seems nearly impossible anyway, and who is going to be there in the future to do it. Humidity would play havoc with these kinds of adhesives.
If you're going to dry-mount, you can mount directly on the aluminium - it's a more stable substrate than buffered mounting board.
Also, if you mount using heat-activated, non-acidic mounting tissue with a paper layer in between the two plastic layers, it should be easily removable just by applying heat. I personally wouldn't use the pressure-sensitive tissues, though, as the adhesives in these are non-removable and more susceptible to degradation.
Have you considered using hardened gelatin as a 'glue'? That stuff sticks pretty well to photos, and can be dissolved later on. (I'm not sure how inkjet prints would respond to a hot-water bath, though).
What I'm going to try with my own work this month in a 40x60 size is to dry mount the print to 4 ply rag board and then mount that to aluminum using the PVA book binders glue. That may be a mess to keep flat or it might not. I'll find out. That PVA is like concrete when dry and used by great museums to restore rare manuscripts and such.
That's the problem - it sticks so hard that it's near-impossible to remove for future restoration! This is a problem they're now encountering with books bound using PVA.
Also, PVAs come in a variety of types - some are quite acidic, others are neutral to slightly alkaline. You don't want to use an acidic one...
I am wondering about one thing though. Would it be doable to paint the aluminum dibond with a titanium white acrylic to seal it completely and dry mount to that? I want to try that also. I know that dibond comes painted in black so I see no reason not to paint one white myself before dry mounting to it. (unless the dry mount press melted the acrylic paint in some way?
Why would you do that? Paint peels. That's just another layer which can peel.
If you use anodised aluminium or anodised titanium, it's also sealed completely. Even straight aluminium panel is sealed completely by an oxide layer, although the oxide layer there is much thinner than that of anodised aluminium or titanium.