My first inclination would be to simply take the stack of spreads after printing them and put them into a paper cutter and cut off the excess paper.
That being said.
You can certainly center them using your printer options in the print dialogue box when you go to print the PDF but I am not aware of being able to add a border in the printer options.
If you want a border around the pages you should first open your original InDesign Document and go to the MASTER PAGES and draw a border on them. Then re-output your PDF as spreads and then print it centered in the page.
That's the best advice I have regarding the situation. You might consider using LEGAL paper. Then your extra white space would be on the two ends and not across the bottom of the page.
If anyone else has any bright ideas feel free to jump in. I guess I'm struggling with why it is such a big deal to have the extra white paper space on the print outs?
I had a draft that started with the question "What defines presentable here?" Which is the same question as "why is (whitespace) such a big deal(?)"
I'd do something similar as you suggest doing with the master page dodge - I'd make a new blank landscape lettersize InDesign file, then place the 8x10 pages into that. In this way I could get complete control over the, er, presentation, without making changes to the source file I wanted to present. It's a minor difference, but it might be easier to handle.
You made me smile this morning with your post. Because that is exactly what I was going to suggest then decided it might take too long to fully explain so I went with the shorter suggestion. But we do have one client that we produce these large folders for that end up being 4 to 6 panels wide (each panel being about 9" x 12") They fold up to a final size of about 9x12 but unfold accordian like. Anyway the proof is 40 - 60 " wide by 12" tall. The customer doesn't know how to tile large pages out of the full size pdf so they have asked that we send the proof in pages. One panel per page. So like on a 4-Panel folder we will have 4 outside panels and 4 inside panels (total of 8 panels). So we create a new document that is 8.50x11.00 that we call PROOF + the name of the document and in that document we place the original InDesign file but we crop it down to one panel and shrink the panel down to fit the 8.50x11.00. (The customer doesn't care if it is at 100% size or not) Then we do that for each of the 8 panels so the PROOF document has 8 pages in it and has the original InDesign file placed in it 8 times. 4 times with the page 1 placed and 4 times with page 2 placed. Anyway we produce the PDF from it and the client gets a PDF that is 8 pages of 8.50 x 11.00 size. They are able to print those pages out and read them and they are happy. What's cool is like you mentioned. It doesn't change the original document and when they approve the proof we have our full size document ready to go into production. If they make changes to the proof we go back into the original document. Make the changes. Then close that document and open the PROOF document and it of course will want to update 4 or all 8 pages depending on whether we made changes on both pages or just one page. Anyway after updating the links we simply output the PDF proof from the PROOF document and it reflects all the changes we made in the origjnal InDesign document. So the whole process of giving them a panel by panel proof is quite easy once you have everything set up.
I was going to suggest that but was too busy/lazy last Friday so just suggested putting the border on the master pages of the original document. But your suggestion is better. As you point out it would allow them total control over the presentation and would NOT ALTER their original document in any way. It would allow them to do ONE border around both of the pages in the spread if they wanted. And once they produced the PDF from it if the customer made changes they could easily make the changes on the original document. Open the second document, update the links and viola! Be ready to present a new proof that looks exactly like they want it to for presentation.
If you do not fully understand what we are talking about feel free to ask more questions. I'm feeling totally refreshed after the weekend and will be happy to help as I am sure Joel will also. I started in printing 35 years ago back when you "pasted" the artwork up using wax! So I've seen alot and since the entire process has moved onto the computer platform it can be complicated at times. It is not as easy as learning how to use a word processor.