99 def is literally shit for edge pking, and tanks are shit when it comes to bridding in general, so...
Here are some def options for you:
a) 40 def - great antirusher, has the acces to common, yet still good rune gear, decent combat level, can even face pures. Optional prayer levels - 12/13, 44/45, 74. (I did exclude 52 prayer, because range tanks should never pk in any other worlds than high risk).
b) 60 defence - often underestimated, possibly the best level if you're planning on getting rigour. Still fairly low combat level, d med pride! Same optional prayer levels apply.
c) 70 defence - unlocks great armour, destroys rune/zerker pures easily. Same optional prayer levels apply.
d) 75 defence - should be only gotten if you have rigour and the money to afford a divine/elysian. Otherwise it's just a waste of combat levels.
e) 80 defence - same as the above, except 80 def is for pernix.
f) 90-99 defence - you're in the mid 100 cb bracket, you get to fight 85+ attack 99 strength zerkers with turmoil, 99 def can barely tank my 78 attack dher. Strongly advised against.
GOOD LUCK
Gear and set up:
Common set-ups are usually about the balance between a fast weapon, that deals damage quickly but isn't capable of doing 'big hits' and a weapon that can do the finishing blow. Some examples:
- Magic shortbow to rune crossbow with rune/dragon/onyx, hand cannon or dark bow
- Dragon darts/rune knives to rune crossbow with rune/dragon/onyx, hand cannon or dark bow
However, if you're uber l33t, you can prod some yew shortbow to magic comp bow just like I do

.
Typical gear consists of some black d'hide body, black d'hide chaps or melee platelegs, best melee helmet you can wear, snakeskin boots, a glory and maybe a granite/obsidian shield.