Over burdening recommenders?

Just thought I'd throw this out there. So I've already fired off 5 applications, and though everything's gone reasonably smoothly so far, I'm starting to think of contingency plans in case those 5 (4 of which have <20% acceptance rates and the other, Duke, didn't offer me an interview) don't pan out. Since I obviously don't want to get stuck competing against a stacked deck in various school's round 3's, I know I need to apply R2. That said, it will only be a matter of 2 weeks or so between when I get my first R1 decisions back and when the R2 apps are due, and said 2 weeks are right in the middle of the holiday season.

Therefore I ask, is it unreasonable to send an email next week 'bracing' my recommenders for the possibility of having to write 5 more rec's, but also stating I won't know for sure if they'll be needed until Dec 22 or so?

Reasons for: Being a Peace Corps volunteer that's returning to the US in June of next year when I'll be 28, I think this is clearly my 'peak value' year. I can't see myself suddenly building a stronger app next year, and I really don't see the point of working somewhere just for a year either.
-As a PCV, I can get most if not all of my application fees waived. For every app I submit, I am increasing my percentages, with little recourse. I am confident that I can submit a quality application for each.
-These rec's are clearly the best ones for me, 1 is my current boss and the other is well-versed in app writing / knows me well

Reasons against: My rec's already put a lot of time into my first 5 and I'm sure have better things to do over the holidays. And I'm sure they'll wonder why someone really needs to submit 10 applications.

Thoughts? And yes, both recommender's have already received a nice amazon gift card for their work