It is good that you are able to do as much exercising as you and your friends do ,sadly at this moment we seem to be at a point in time where we have few options as her PD has finally taken off and is hurting her without mercy.
She is approaching this upcoming October ,16 years since her PD Dx and as you are, she is a very accomplished artist and continues to paint for short spurts of time throughout the day.
She did have 2 prominent areas of difficulty that helped us get to the Physician that eventually led to her Dx of PD.
The first was her right arm did not move in concert with her left arm when walking ,the second is a curiosity as to why she could not get up out of a chair and had an unusual hesitation before she could move from a sitting to a standing position.
We do as much exercise as we can (we also have to climb 102 steps to access our home) and she loves crossword puzzles and advanced Suduko games.
Her mind,and it;s cognitive actions is not affected by PD ,her voice even with LSVT training is low recently I think Apple have created an Iphone or smartphone application device which I have seen in trials here at our hospital in New York City that listens to your voice and when it is to low and NOT understandable by others a beep appears in an earbud attached to a patients ear that alerts them to the fact that they cannot be heard.
It always surprises me as well (I do not wish to appear negative) how much she is able to do as compared to other patients in the 3 PD support groups we attend every month at hospital.
Driving so far is not an issue, but no longer is it possible for her in our large city. We drive on visits to her mom in a small city far away from New York City with little road traffic.
My wife has used her strange calligraphy related to PD which looks quite like Sanskrit to her advantage in her artwork. a kind of Scraffiti .
Thanks for communicating with me on this forum , we go to a very top notched PD Neurologist in a week it is at the same facility that many international folks go for PD treatment who are very familiar with my wife's history and I am happy to report back here what we may all come up with.
Yes! her PD which as you have mentioned about your self creates no tremors ,shaking or dystonia but stops movement without warning & falling ,thankful for us she sleeps all night but with the oft mentioned nighmares and mild hallucinations, forgotten by her ,upon waking up.
Good wishes to you in the UK from the start of our war dead Memorial day holiday here is the States,