It's my understanding that GM detect hidden gives you 5 lockpicking. So 95 lockpicking and GM detect is the same as gm lockpicking I don't know if this is close or not. http://uo.com/wiki/ultima-online-wiki/skills/cartography/
I was on there a few days ago and I remember the bank had tmaps inside of various quality. I remember one of them was "deviously" drawn. I don't know if it has exactly what you are looking for though.
Level 6 map takes GM detect and 95.1 real LP. I made the mistake of digging up a 6 with (95 LP real and GM Detect) and it spammed in channel a level 7 was dug up! Ron recalling around found Air and I sitting there with me the T hunter unable to open it! What ensued was 45 minutes of PvP when two other groups found us. Fortunately Bart came along unlocked the chest, ran with the map to safety and surprised me by handing it over. Long story short you need to train on dungeon chests to 95.1+ LP real or just do lower T maps to gain. GM cartography, very easy to do and 75 won't work on 6's. Level 6+7 are where it's at for high level mobs rares and team work if your into that. Provo mage T hunter is a great template.
You can gain on sixes but you'll fail a few to many times like you can on fours and fives. At 95.1 (after I learned a hard lesson that 95 real is not enough with GM detect on my first level six) on my second level six I was starting to wonder if I was ever going to stop failing to pick the lock.
On a side note: I gained from 95.0 to 95.1 by lockpicking a lvl2 tmap chest. Oh, and from what I know, Detect Hidden doesn't influence the ingame success chance of actually opening a chest. It just enables you to start opening the lvl4 chest in dungeons without the REAL value of 95.0 in lockpicking.
This is correct, it simply makes you eligible to attempt them sooner. It has no bearing on success rates