Peenemunde only appears to have 2 usable parking slots (out of 140+)

[Pizzicato]

Placing more than two aircraft at Peenemunde results in a No Parking for Aircraft error.

[western_JPN]

In my testing Peenemunde in DCS 2.9.15 .9509 (not changed from .9408) , besides historical operations, 
slots 77-87 are very narrow size limitation for fixed-wing aircrafts.
Even Yak-52 cannot be placed in those slots as start from Ramp.
Christen Eagle II can start from slots 86-87 but not 77-85.
Ka-50 III / UH-1H / SA342 helicopters can spawn in slots 77-87.
Even rotary-wing ones, Mi-8 and Mi-24P are too big and only slots 77 / 84 / 85 / 89 / 92 are available in whole of Peenemunde.

MiG-21bis / MiG-15bis / L-39C can spawn as same as Christen Eagle II (total 134 slots ? available).
MiG-29 or Su-25/T are a bit limited but over 110 slots available.

Su-27 can spawn only in two slots 89 and 92.
Yak-40 or An-26B / An-30M are only 89.

IL-76MD or similar / larger size aircrafts are unavailable.

[Pizzicato]

That's some impressive investigation, @western_JPN. Nice work.