I was actually in a similar position to you last year, in that I was couples matching with my wife (internal medicine) but didn't have the time or resources to interview for prelims in every city in which I interviewed for rad onc programs. My solution was to interview for prelims/TY's in the cities where I could get to the interivews, and for the rest go with the plan that I would scramble into a prelim (likely gen surg) if I matched a rad onc slot in that city.
I checked with my dean of students about the feasibility of this, and was told that on Match Monday (when you login to see if you did/didn't match), along with a list of which students didn't match, the med schools get informed which prelim/advanced program each of those students matched into. As it worked out, I indeed matched into a rad onc program in a city where I didn't interview for any prelim slots, and found out where I was going that Monday such that I could scramble accordingly, which I did into a general surgery prelim program. While it's no cush TY year, I'm actually really liking it, it's way more fun than rounding for 6 hrs every morning on internal medicine, and this way I got to be in the same city as my newlywed wife for our intern year.
FYI, virtually every city I looked at had unmatched general surgery prelim slots open through the scramble, and the program i matched at was pumped just to have a prelim fill the spot who had a matched program for the next year (and wouldn't try to work their way into a categorical spot). So getting a spot in the same city if you're willing to do surgery wouldn't be a problem.
All that said, it was pretty stressful dealing with all the uncertainty, but in hindsight theres's virtually no way it wouldn't have worked out. Feel free to hit me up with any specific logistics question/concerns you may have... and GOOD LUCK
Thanks for the advice. My wife is a cancer researcher doing her post-doc now and will be starting a new position wherever I match for Rad Onc. Since she will need to move to that city right away, I can't just hang back one more year at my home program. (Maybe the current lack of grant money available will eliminate our problem all together.)
Are there any resources to figure out how many prelim spots are being offered at specific programs? Applying to programs with many spots would seem to be the right strategy.