Hi Tore,
yes you are right your old lady needs a little make up, because she is a bit rusty (see attached pics "0009", "0013", "0026" and "0029".
I suppose preservation is very difficult because U-995 is not an indoor presentation like U-505 in Chicago. So the ravages of time won't reprieve the boat.
I haven taken two pictures in addition which assist your thinkings about model scale, rivets, carving, canning and denting. If you have look at picture "0006" (stern) you can recognize how small the rivets are. Picture number "0022" is a very rare one from the flood holes at eye level. You can see clearly the frames of the inner structure through the flood holes. The drip channels at the lower left side are not accurate because they just for draining the rain and dampness (as you've mentioned before).
Regards
falo