This is exactly what I did and there are quite a few of us doing this. I decided that with a 170, I could get rid of my other car that just sat for about 7 months of the year. So, I traded my small C and my Toyota Sienna in on a brand new 170.
I get about 12 mpg in town and 17/18 on the highway at the speed limit. The Chevy is a comfortable drive. It fits in a standard parking spot, but of course, you are height restricted. I tend to still park far from the doors to save the sides from the usual dings.
One bit of warning, it is very difficult to get insurance if you do not have a car. The company that had insured me for years... for about $1200 a year for the car and RV suddenly jumped the premium to about $2400 for one RV. It took about two weeks of phone calls and I found that companies like Safeco or Progressive or AAA etc will NOT even insure a driver with only an RV. I finally went to FMCA figuring that they had experience with this. The second catch was that there are a number of options for full-timers... but I wasn't eligible for those because I, like you, have two homes. And having a stick house makes you ineligible. The only option they could offer me was National General and raising it to the highest liability rate is about $1100. (but another person on Roadtrek Owners page on Facebook said that they refused her) Another person said that she got insurance with Farmer's Insurance. So don't expect to save much money on insurance.
Another option which will give you more living space is to consider the new Roadtrek Zion SRT which is about a foot longer than the 170 on the Promaster chassis. But if you are thinking used, the 170 or even the 190 might work for you.