There's also the method
1. Dig the map, fight the monsters one at a time (have a rune marked a few screens away, and precast recall/sacred journey as spawn pops - actually safer than invis/hiding, or have a gate precast, then walk back to chest, drawing 1 guardian spawn at a time into solo battle)
2. go home and soulstone off cart for LP
3. Go back and pick chest
4. untrap however you can (is TK still possible off SP? Or just pop the chest and tough it)
5. dig the chest slow enough to where you never fight more than one thing at once.
6. when done, go back and put cart back on for the next dig.
I've just returned after over a year of dealing with multiple family and health issues, but before I left I could do up to level 6 maps (well, everywhere except Tokuno) with a melee paladin that actually kept both Cart and LP on at all times (template uses skill equipment to get 120 swords & tactics, 100+ anatomy, parry & healing, GM cart & LP, and 80 chiv), so I could skip parts 2, 3 & 6 above. If I went the above "swapping" route, I'd be able to add GM Resist, but I find it easier not to swap. Plus, as a human I can cast low level magery (TK can be cast at 0 skill with 25% failure, 100% success if from scroll) and spellweaving (gift of renewal is great even at 0 skill, if you get a high level focus - pile a bunch of non-spellweavers on the circle and cast arcane circle - and the 1-slot summons are great distractions for spawn).