This is another of my Maya pet peeves! There should be marking menu options for ALL views including BACK and RIGHT and BOTTOM.

What you have to do as it stands is go to predefined bookmarks and select one of those ORPHANED views and it will reassign that view to the CURRENT viewport but does not change the name (for the love of god!!!).

So that now you will have a persp view for instance and it will be the BACK view! It's the very definition of RETARDED!

You could create another camera for each of the orphaned views and assign them to the new cameras. Then you could attach images to the camera, then create links on you shelf to the orphaned views and after 40 minutes of diddling you can have a cludgey way to do what you should have been able to do from the freaking marking menu in the first place (lol).

Rather then pull my pud for an hour setting all that crap up every time I want to model I just do what was suggested earlier and create plane for each of the orphaned views and then put them on a layer and toggle the opposing layers on and off as needed. It's still a cludge but I find it the least annoying solution.

Messing with view port in maya can be one of the most confounding exercises ever! I have been using maya since maya 3 (over 10 years) and I still get wrapped around the axle trying to figure out view ports. Just recently I ended up with all three of my orthogonal views so hopelessly messed up that every time I loaded maya I got a nasty gram saying it could not find any of the standard views and was creating all new ones, then I would end up with 7 cameras and top1, front1, side1 OMG! I was ready to toss the machine at the wall! I had to completely blow away my maya start up folder and regenerate everything then rebuild all my shelves. As a result I do not try to do anything with view ports anymore. I just sit and grumble and stew every time I have to have a right, back, or bottom view!