Divin'Hoosier:
But for my own planning............?
Jim.....
As the rule is 130 feet TOTAL from the surface AND into the ship from the exit; typically, the deeper the dive, the less penetration you would be able to do (assuming you are staying within the standards). However, in our neck of the woods, we dive artificial reef type ships which have been prepared for divers before sinking. They have emergency exit holes cut into the sides periodically enough, that you could dive to 110-115 ft and run the length of a ship (380 ft +/-) and stay pretty close to the standards.
Although it is wise to train at shallower depths, I highly recommend getting some deep penetration experience, while still in the care of your instructor. Handling emergencies while the effects of narcosis are present (whether you think they are or not, your thought process is affected) can create anxiety quickly which could lead to panic.
My first real penetration (dive 4 of class) was at 115 ft, and about 180 ft into the ship (exits where visible in about every other room we passed). In the end we had to deal with: an instructor who lost us by getting too far ahead and didn't notice we turned, total black out from silt (another group passing us), subsequent deco (first time) due to delayed exit time, tangled reel in the dark, tangled fins in line, etc. Although this all created enough anxiety to get close to panic (especially about what to do about the missing instructor), I am very grateful for the experience of having to sort out the issues at depth.
(IMO) I would not think sending a newly "wreck certified" student (that had only trained to 60-80 feet) out as a certified wreck diver, would be prudent. If you can, get some deeper experience. And if you get into just a little trouble that you have to deal with, while an instructor is around, it is probably even better in the long run.
Note: If you only train at shallower depths in your class, don't go deeper without someone who has had more advanced experience. You could VERY easily get yourself into trouble.
Good luck. There is nothing quite like wreck diving.