Townhouses really aren't all that common here. Condos can be found, but not nearly to the extend you'd find them in other parts of the country. Much of our housing stock is older and most rentals are in those older buildings. It's much more common to find an old mansion divided into 3 or 4 rental units than it is to find newer rental condos. You may be better off looking at some of the better apartment complexes nearby (not that there are tons of those either) and checking craigslist for the occasional available condo that may pop up. Traffic around Raynham tends to be just fine. It's not close enough to central Boston to be too affected by daily rush hour traffic.
Look for stuff in Raynham itself (it's nice off of the commercial stretch of Route 44), Bridgewater (nice little town center with a small college), Mansfield, Norton, Easton, Lakeville (I know there are some Lakefront rentals there), Freetown, and Middleborough (nice town center, fairly rural outside of that).
Taunton is right there and will probably turn up most of the rentals in your search, but be careful. Taunton covers a huge area, and while parts of it are rural (see: East Taunton) and nice, the center of town is fairly urban and rundown (albeit, with a nice little town common). Same can be said for Brockton except that it's a larger urban area than Taunton. Given your criteria, I'd avoid most of Brockton/
Bridgewater and Norton are nice, but you may find that rentals are more geared to college students.
Lakeville has some nice, newer rental units at
Kensington Court right next to the train station. It's just off of 495 so the commute to Raynham would be a breeze no matter what time of day. Also in Lakeville, you may find some nice small cottages to rent (many of them lakefront). These were mostly older vacation homes that have been winterized for year-round use. Perfect for a single person.
Freetown won't turn up much, but if you do find something, it's quiet, nice and safe. Mansfield and Easton are both safe, suburban communities. Anything there would be good.
While I'd tell you to avoid just about all of Fall River, the FAR North End (along Main Street by exit 8 off of Route 24) is loaded with newer apartment complexes and there are some condos for rent in there.
Four Winds is one of the units there and it's nice enough. This region of the city is suburban in nature, safe and feels very disconnected from the rest of town (which is fairly rundown). I'd also look at
Royal Crest on Highland Avenue (also quiet and safe).
New Bedford will be closer to the 30 minute end of your commute (traffic is rarely an issue along the route) but may offer some decent last-resort options. It's the polar opposite of what you requested (a less-populated area), but
the Regency in downtown New Bedford is very nice. It has parking, great views (Martha's Vineyard, Buzzard's Bay, etc) and you can walk to a good number of shops, restaurants, museums, etc. New Bedford also has a few nice Mill Conversion loft apartments worth checking out.
The Lofts at Wamsutta are very nicely done. It's bounded by highways on two side (18 and 195) and the rest of the neighborhood is a bit ugly (but not dangerous), but the complex itself is very large and set off nicely from the rest of the neighborhood with a gated parking lot and secure entrances.
The Victoria Riverside in New Bedford is brand new with townhouse lofts. It's well located for commuting and while not unsafe, the neighborhood isn't charming (again, a little older and rundown). The water frontage at Victoria isn't as nice as they make it out to be (a work in progress), but it's not terrible. The units themselves are very nice (I toured them).
I think finding condos and townhouses to rent may be tough, but hopefully you'll find a reasonable alternative. The lack of new, nice, affordable rentals is one of the biggest turn offs many people have about this region.