Good to hear you're almost at that "gone fishing" stage in your 5th decade! I'm also a newbie here, having just acquired a mostly unused 2001 RT170 with only 12K miles. My wife & I struggled between the 190 & 170 mostly because of the sleeping arrangement. But after watching a 190 struggle coming in and out of a normal parking lot (home depot my favorite store), a tight residential street (live in SF) and considering the weight of 2 additional feet of steel box, we felt lucky to find our RT170 on Ebay for a price we can afford. The smaller quarters is quicker to cool & heat, and it really forces you to live minimally, be organize and be mindful of the sequence of how you do things.
Driving 1200 miles on 3 trips the first month, we feel comfortable with our rig. The 170 sleeps across the back lounge area - we're both less than 5'-9" we fit just fine. I removed the TV cabinet that hovered over the one side of the sleeping area. Hey, but you as an engineer (me an architect) we like to solve problems...I'm exploring extending the back by opening the back door, cantilevering the back board an extra 24" and employing my wife's sewing skills with a tent like cover over the whole thing, thus allowing us to sleep the other way. I'm a DIYer...so I get excited about future improvements. I believe RT offered the "Florida room" as space extension under the awning with screen netting - mine doesn't have one and I've never seen one.
Towing a vehicle someday is also important to me. The 170 is rated GCWR 13,000 lbs (GVWR is 7700) so it might just be able to tow a Smartcar!
Best of luck with your choice.
2001 RoadTrek 170, Dodge 2500 5.2L V8