The problem with trying to hit a certain PID frame for the roamers is that it might not actually happen, and if it does, it might be more difficult than you expect it to be. Advancing the PID frames is not a consistent thing due to the rain and NPCs. Sometimes your results will be all over the place, sometimes it actually works the way you want it to. In general, it's just not reliable enough to expect you'll actually hit the frame you want.
From experience, I have to agree that it's easiest to find a frame you can hit, then restart and RNG your IDs to match that frame. It may take more time, but it guarantees that you'll get it without really any trouble. Trying to blindly hit a frame is just too much trouble otherwise, IMHO.