I hit Germany in general and Munich in prticular whenever I get a chance to visit Europe. You just can't beat that bang/buck ratio anywhere in the US.
But there's a catch. If you are planning to visit Munich, avoid the Oktoberfest weekend at all costs (in spite of the name, it starts at the end of September). Oktoberfest is the excuse for all kind of people (particularly those unfortunate italians who are stupid enough not to have places like this in their own otherwise beautiful country and end up pretending they love beer just to hit up the FKKs).
Anyway, those places are so jam-packed that it's not fun anymore. You'd think that people would start going home after midnight, but no, that's when the party starts. As you assume the place couldn't get any more crowded, the male components of a Bavarian music band trot in after work. I literally had to wait in line on the stairs with the girl for 15 minutes for a room upstairs to become available (only upside, I got away with groping that luscious ass the whole time). As a girl and a patron would appear at the top of the stairs (signaling their performance was over and a room was finally free) they'd be greeted by cheers of everyone else waiting (I hope those dudes were not shy). To top it off, some german guy was accompanying his blind friend (white stick included) forcing everyone to move. I actually find this commendable, but it did add to the oh-shit-where-have-I-landed spirit.
Girls were increasing prices. A 100 euros performance was now sold for 150. The little movie theater (normally empty) has been constantly taken by people fucking (and others patrons going by could take a sneak peak at total strangers fucking through the strip curtain.).  

Long story short, if you’re thinking of using Oktoberfest as an excuse to hit up Munich, don’t. I’m still here as I write this, and I’ve already decided to rent a car and get as far from the city as I can tonight.

I was in Munich this last weekend and visited Sunshine FKK there on Friday night (9/27).  Exactly as you said, it was crowded with Italians, but I was there by Uber, and decided to tough it out as the car had left.  I arrived around 10:30pm and had to stand in line just to enter, but it wasn't too long, maybe five minutes or so.  The entry fee was 80 Euro, I expect it is a raised price during Oktoberfest.  Once inside and after paying the entry, I opened the door to the locker room and was shocked to see several women standing there waiting to be paid (there is no separate smaller locker for wallets) and several men trying to move about to dress and undress.  It was chaos.  I undressed, grabbed my towel (no robes provided) and headed into the club to explore.  It was small, with several rooms but most of the people were concentrated in the entry foyer, bar area, and smoking area.  The other rooms were totally empty like a "living room" area that had a nice large sectional sofa and kitchen.  After making a few laps and beating away a few energetic ladies, I found a small hallway between the foyer and smoking area which seemed quiet and safe where I could get a feel for all the girls working that night as they would pass by me - maybe 20 girls.  Several stopped and gave me their "pitch" and one said "there is a 30-minute wait for a room." I did another lap and had a good feeling about a girl I met on an outdoor patio, she is from Moldovia named Selina.  She said we can get a room "immediately" for 300, so I said yes.  She complained a lot about the Italian men there stating they "don't spend any money."  I realize this is triple the cost, but I was tired from a long day of drinking at Oktoberfest and knew it was also for "tip" money to the guy managing the bedroom keys, lol.  We went up the stairs, and right into a room.  A nice big room too.  We did the normal activities, and I loved it.  I left soon after my time, and noticed an even longer line outside waiting at midnight when I left.

I have gained a lot of experience with the FKKs in Frankfurt, so this was fun to see a smaller FKK in a different city.  It is of no special value, and I would only return if I am in Munich again with a few hours available - I could literally spend an entire afternoon and evening at the ones in Frankfurt.

Sunshine is a great place. Yes, it sucks during oktoberfest, but I find it nicer than many larger establishments in all other times of the year.