Instance grinding lowbie clones - exp distance?

So my initial inspiration for dual-boxing was getting sick and tired of the utter lack of tanks on my server and deciding to role my own on a new account. I started a warrior, did the quick 1-10 grind, and then fired up my hunter and headed off to deadmines.

Only trick is, a level 10 in deadmines is an aggro magnet, and even when one-shotting everything at range with my hunter the quarters are close enough that if I have my warrior on follow it'll tend to pull anything and everything in LOS. This becomes an especially tricky issue when trying to negotiate the little zig-zag ramp to the top of the ship where she has a tendency to pull a boss and upwards of 10 adds and die before I can tear everything off of her.

So to solve this (at least until she's high teens/low 20s and won't pull everything in sight), I was figuring I would take the alt off /follow at the start of an area and part her out of LOS, clear ahead as far as possible, and then move her up before my hunter gets out of range for her to leach exp. Only problem is I have no idea how far exp distance is--I borrowed friends' accounts and geared a couple alts out of instances and I know that in some places I can clear practically every boss and the alt at the door can still roll on loot, but does the same hold true for exp? Is this just something I need to guess for myself and just keep an eye on when my clone stops getting exp, or is there a rough rule of thumb to follow?

In terms of deadmines, you can run about half way to smite and keep killing all and still get xp. Hope that gives you an idea. Or another example, in SM library, you can park alts at the door to the quadrangle (where Locksley is in the room off), and kill all the mobs in the square and your alts will still get XP. and another, in Cathedral, if your alts are parked at the door in front of the fountain, the limit is around by the steps up to the 2nd level.

I'm not good at estimating real world distances, but its around 80 meters/yards?

EDIT: As a side note, In case you don't know, levelling with only 1 alt and a 60+ is slower than levelling with multiple lower levels, e.g 1 70 and 4 10s in Deadmines. It works on average levels for xp in instances, so inviting along guildies or even randoms for the boost will speed the XP gain.

How high is your hunter?

I regularly use Deadmines to get from 10 to 15 when stockades can be accessed...

And way I do it is to use the pet to agro everything to the next door, then bring them back for an explosive trap or two* (if timed right). Then wipe everything and repeat. My hunter is 70 so that might be an issue.

*I use eyes of beast to run the pet round attacking things they then agro each other. Depending on the area I'm trying to tank I either use Dash (cat pet**) on the way out run back slow or dash on the way back (or if really big area both ways :D). So I hit explosive trap, hit eyes of the beast, run round a bit, then pull back onto the trap which has no finished cooldown. Mobs hit trap, then hit me which breaks eyes of beast. I then slap down another trap and most of everything is dead. And I use that pretty much all the way up to BRD. Varying the size of the pull obviously, 90,000 Dark Irons will dent even my armour :D ((lvl70 mainly blue geared hunter (21/37/3) best stuff is a mainly complete D3 set armour))

**Pets with good AoE are even better at this as they hold the mobs better than single target growl. Have had good luck with an Owl (for Screech) (one from Skettis) but hate the big flappy wings, if pets weren't such a damn pain to level I'd like to try a gorillah for the foot stomp.

Yeah I found out recently about the group bonus thing, I need to see if I can bring a couple scrubs with me or I might just get a third account (although I don't really want to start 3+ boxing until I start a proper squad).

Edit: My hunter's 70 is a mix of heroic blues/kara gear. I never actually considered the pet pull+explosive trap bit, that sounds potentially quicker than just one-shotting everything individually.

i find the explosive trap method works great till SM or so, after which it's quicker just to DPS them one by one. I put the pet on agressive and let him select the targets, then I have an /assist petname macro which I spam and just 2 shot everything.