how do i tighten up my golden doodle's skin?

my mother is moving in with me and, at my insistence, bringing along her golden doodle who's 17mo old. she bought the dog against my advice because a couple of her grandkids are *deadly* allergic to other animals. she was totally devastated when it turned out to be WAY too much dog for a senior with medical conditions. my mom was told by the breeder that loosey would be "small to medium - maximum 35lbs".

HAH!

Loosey turned out to be quite a bit larger than my mom expected and WAY too much energy. the jumping, chewing, barking, etc, was impossible for my mother to control so the dog spent much of her life in a crate, only being let out for a few minutes at a time to "do her business". as a result, Loosey gained so much weight she literally looked like a curly-coated pig, complete with waddle. i tried to walk her and it was a fiasco - the dog couldn't go even half a block without having to stop and sit down for a bit and forget doggy things like jumping up onto park benches or running up the stairs.

months of lecturing my mother and finally threatening to take the dog from her finally got her to get someone to walk the dog on a quasi-regular basis, stop locking her in the crate all the time, and stop leaving full bowls of crap dog food lying around. Loosey has lost weight and is now about 65lbs or so. it's to the point you can *almost* feel her ribs (you still have to dig for them through the fat pad around her torso) but her skin!

i'm not kidding: i'm going to a circus and have her billed as "the incredible melting dog" because when she lies down, it literally puddles on the floor! when she walks, there are large, loose folds between torso and hind legs and there's a flap of skin running down underneath the length of her body from chest to stomach. my mom thinks it's "adorable" but i find it deplorable. it makes me angry to see it because it was all so unnecessary and so easily prevented.

does anyone have experience with this? given that she's still young, will her skin tighten up with a proper raw diet and daily exercise? i am a devout walker - if i don't walk my own dog at least 6 miles a day, he's bouncing off the ceiling. if it's too hot to walk, we go to one of the local water bodies (can't walk 5min without falling into a river or lake where i live) and swim. Loosey doesn't know how to swim but i expect it'll be easy enough to teach her as both goldens and poodles are water dogs.

will massage help tighten up her skin?

any other ideas?