real time clock drifting off

While a little unpleasant due to the size of the parts, since all the parts you need to add are two terminal devices, it definitely can be done with an iron. Honestly, for two terminal parts, even small ones, I find soldering iron to be easier than hot-air. I only use air for large or no-lead parts.

You put a bit of solder onto one pad for each part, hold in place with tweezers, and melt the solder on that side to solder that end, then go back and solder the other end. Might not even need additional flux.