Some advice on a wheelchair for Mom, please.

My soon to be 87 year old mother has been fairly active with no serious mobility issues until a Sep 2017 fall that injured her knee. She is "protecting" her knee to the point that she doesn't want to put enough weight on it to use a walker. Both her doctor and the PT tech believe she will recover enough walk again with a walker in a few more weeks, but that's not the case right now and she may need a wheelchair for long distances even after she is mobile again with a walker. I'm also thinking that during winter months, the chair would be safer than the walker when getting Mom out of the house and into the car. Mom has been accepted into an adult day care program but will not be up to the long walks getting into and out of the building for a while. After looking around and consulting with the PT tech, we identified the desirable features for Mom's chair: flip back arms (to aid in transfers and so the chair will roll completely under a dining table); leg lift extensions so her feet won't swell when in the chair for several hours at day care; large front wheels so the chair will move easier on outside surfaces; an 18" seat width; and a lightweight model (less weight for me to lift when storing the chair during car rides).

Medicare will not pay for a light weight chair or one with flip back arm rests. We can afford the lightweight chair we want, but now I'm wondering if I'm over-rating some features and would like some feedback from people who have experience using wheelchairs. The light weight model is rated for 350lbs and my mother is about 180lbs. I have some back and knee problems of my own and think lifting 38lbs of wheelchair into the car would be better for me than lifting 54+lbs of the "standard" chairs. The flip back arm rests so the chair will roll completely under a dining table and Mom can sit at her normal place at the table during meals or pull the occasional table in her bedroom over her lap for her books/newspaper or sewing stuff seems very desirable to me too. The day care uses tables for a lot of their activities too. Although she can fully stand for transfers now, if the time comes in the future when she needs bench transfers wouldn't the flip back arm rests work better for that too?