Last year I purchased a Thule parkway 4 bike hitch for a 2" hitch. I use this on a mini-van that has a 2" hitch to carry up to 4 bikes. Sometimes I would like to leave the mini-van at home and use my Mazda 3 for short trips with only 2 bikes max. Unfortunately I can't get a 2" hitch for a Mazda 3, so I either need to get a 1-1/4" hitch and use and adapter or maybe get a trunk mount rack.

Does anyone have any experience with using hitch adapters? I read on one site that sells these adapters that if you use the adapter the tung weight should be reduced to 50% of the rated tung weight of the hitch.
So in my case the tung weight would be reduced to 100 lbs (from 200), which seems OK for a 32 lbs rack and 2 30 (ish) lbs mountain bikes.

The other option is a trunk mount for the Mazda 3.

Any options on these options?