Short Answer : Don't.
Long Answer : Stealth provides far more than just armour and using it properly will help your survival rating.
Boxing is a naff attack that Blasters really don't need. Tough won't give you enough protection to make it worth 2 power and 3+ slots.
Getting the Fighting pool and sacrificing Blaze and Fire Sword? Don't do it man! 
World of Jackcraft.
The percentage resistance on tough is so low (I really can't remember the figure off the top of my head, but I think it's ~5% base) it does virtually nothing for you even slotted.
Just some very quick thoughts that I had from scanning through that build, in no particular order:
Blaze is a very good attack, exceptionally good damage when slotted, I really wouldn't advise ditching that.
I find fire sword preferable to flares given the long animation time on flares - I actually just don't have time for flares in my attack chain.
Getting rid of rain of fire is a good idea, it's only really useful if you regularly team with someone who can slow/immobilise. Plus it's such a hated power by tankers from people using it badly that even if it's used well it tends to be badly received.
Another pool suggestion - air superiority - quite handy for bosses if you're soloing on a fire/fire. I've got that slotted with two acc and one recharge and I can keep most bosses on their bums pretty much permanently.
The leaping pool can be very useful on fire/fire, most particularly in the 30-40 range when you're coming accross a lot of mezzers and have no access to holds etc yourself, the ability to absorb one hold while dealing with the offending bad guy is very useful, gives you an outside chance of carrying sufficient break frees. 
Some of those suggestions do gear towards a build that spends at least some time in mele though, and that seems to be something you're trying very hard to avoid so they may or may not work for you.
And the best suggestion of all - try it on the test server first, you'll be cursing if you respec in to something you don't like at level 24 with another ten levels before you can change it.
A couple of you are berating me for dropping Blaze.. but Blaze is in both builds 
What's being dropped is Fire Sword for Boxing
Fire Rain for Build Up
Stealth for Tough
Don't take Flares... that is all.
Stick with your strengths, and Burning stuff is your strengths. You've just got to find the right way to burn em.
That is all
IN MEMORIUM OF GAYBABY
CRUELY TAKEN FROM THIS WORLD WHILE SO YOUNG
Swapping Rain of Fire for Buildup is definately a wise move. Rain of fire is such a team unfriendly power, buildup will show far more benefit, especially with three recharge SOs in there.
I've never had the Fighting pool so I can't comment on that, but compared to Fire Sword, I can't imagine it being a worthwhile choice.
It's not like I use Fire Sword much, I just like taking 1 melee attack and sticking it on auto fire. Anything coming in range gets smacked automatically.
Phase Shift.
If I'm a blaster and everythings went up sheet creek, I can still snipe any major threats / crystals / etc before running away like a madman. I haven't got the power yet, but hey! I got plans.
So I'm thinking of switching from this:
01) --> Fire Blast==>
01) --> Ring of Fire==>
02) --> Flares==>
04) --> Fire Ball==>
06) --> Hover==>
08) --> Fire Breath==>
10) --> Swift==>
12) --> Rain Of Fire==>
14) --> Fly==>
16) --> Health==>
18) --> Fire Sword==>
20) --> Stamina==>
22) --> Stealth==>
24) --> Blaze==>
to this:
01) --> Fire Blast==>
01) --> Ring of Fire==>
02) --> Fire Ball==>
04) --> Flares==>
06) --> Hover==>
08) --> Fire Breath==>
10) --> Swift==>
12) --> Boxing==>
14) --> Fly==>
16) --> Health==>
18) --> Blaze==>
20) --> Stamina==>
22) --> Tough==>
24) --> Build Up==>
Then later when I get to level 44 respec to remove Tough and take my epic armour instead. What do you think, Tough worth it as a Blaster? I'm finding Stealth pretty useless and am not interested in PvP at all.
NB: Can't be arsed doing all the slots, but Tough would have 4, 2 end and 2 res.