Update:

Having had a gut feeling that the above mentioned set-up may not be ideal for my girl, I switched her last minute to boarding at a vet's office. A friend of mine has used this vet for 15 years, they have an excellent reputation. It's a small state-of-the-art hospital that also offers boarding.

I never considered boarding at a vet because their boarding services are usually quite limited but after I toured their facilities I was much impressed and decided this would be better for my girl. The downside was just an indoor run, no indoor/outdoor, and no off-leash time outside. The big plus was at least 3 walks a day, lots and lots of human interaction (huge staff, few dogs) and option of doggy daycare. Now, I am not at all a fan of doggy daycare but again, their setup was quite nice, and  a very controlled environment, with very knowledgable staff. So I booked her one hour of daycare/playtime (either with other dogs or one-on-one with staff). I figured 3 walks and one hour of play is better for her mentally than 20 minutes of running in a small playground and not much social contact aside from feeding and cleaning the run.

When I called from Germany to check on her, they said she was doing wonderfully. All of the staff adored her, and she was "the darling of all dogs there". They said she LOVES to play more than anything, so I was about to order her another hour a day of play, but they said, there was no need, as she was already getting more than an hour, because she was such a joy to play with and was excellent with all the dogs too. They said her appetite was great, she ate, drank normally, and had no diarrhea which is amazing, as she is prone to loose stools.

So after 3 weeks I pick her up, same playful and mischievous and happy dog, she looked a little thin looking down on her and when I weighed her I noticed she lost quite a bit of weight - 9 lbs - although to me and other people who know her it was not very obvious at all. Maybe mostly loss of muscle mass and plus the stress of being in a different environment. They could have upped the food (I left enough for 6 weeks) but I guess they go by general appearance and energy level, and that all was fine.

I would have preferred for her to hunt up some birds instead of playing with toys for three weeks, but as stated above, but it couldn't be done this time.

I will try to take her to Germany next time, she would have had the time of her life! Huge fields to run in, this was just a 10 minute walk from my parents' home, I thought about her every time I crossed it. It's all private land, but not fenced and open to the public, you can even pick apples from the trees!