Following just in case someone has a new cool thing I haven't heard of.
We signed up for a bunch of cards in April, knowing we were headed back to the States for a month in May, then had to do like 21k of MS, IIRC (nothing compared to when we first started travel hacking and got something like 20 cards at once between us, and had to do like 70k of spend in 3 months--about what we'd spend in 3 years!). We paid our taxes (not due til June since we were overseas), mostly did the CVS Vanilla to Money Orders, just cause it's the easiest (miss the days of Amazon payments and Serve loading that was all online, oh well). MS is pretty easy, especially if you don't care about trying to do the perfect method, but just choose the easiest method (even if it costs a few bucks).
We long ago decided that if trying to optimize meant we wouldn't do it (analysis paralysis), we're rather just lose a little bit of translation costs to get it done easily.