I am mounting this project in one of those boards and it did occur to me and tried to position the SOD-123 device would fit with the little leads resting tangentially to two adjacent rings. I thought the adapters would provide larger pads with better power dissipation, but I may be wrong. I will be mounting four units of this device...
Recently I have been toying with one of these other boards which seem to be a little better for SMD. I was able to solder an SOT-23 and 0406 resistors. But not using it in this project.
Back to the round pads breadboard, would you solder the part over the rims of the holes or pre-fill the holes and solder on centers ?
Another possibility would be use a 1206 adapter PCB (
example; $0.3625 per breakout board), as the dimensions should work quite nicely (with nice large pads). And to enhance matters further, they're easy to find and inexpensive to boot.
The other link to various package adapters might be useful as well. Best of luck.
In terms of the PTH dual sided prototyping boards (I prefer FR4 to FR2 <fiberglass vs. paper respectively>), but it's entirely up to you. Personally I prefer to fill the void & solder the part in one go and/or just solder to the rim of the hole.
Please note that my ESD rubber matting keeps the solder from flowing to adjacent holes (PCB lays flat on ESD mat).
Another interesting adapter board and/or other breakout boards for other packages that come in at a much lower price point vs. Schmart Boards (I have to admit that the Schmart Boards are nice though; I grabbed all remaining on the shelves in a Radio Shack that was set to be closed).
Quality is likely be diminished vs. contracted PCB houses however (I haven't the boards the do a proper comparison).
Best of Luck, and I hope this helps.