Lol, at 22.3 inches long, how much bigger do the trucks have to be to be considered 1/8th? The Slayer is just a Revo with different arms, and is actually slightly shorter than the slash.
I just compaired specs of the Slash / Slayer. Over all length is the same at 568mm. Track width both 296mm. Slayer is 7mm taller, or about 1/4" and wheel base is 12mm shorter or about 1/2"
I also checked out Revo specs and the 3.3, 2.5r, and platnum. Seems Slayer WB is between the 3.3 and the 2.5r. It probably uses the 3.3 chassis. With your caster angle....cutting the a-arms down will bring the WB in is my guess.
SCALE? If you go by scaling the CORR Regulations Max and Min WB....the Slayer would have to add about 2 inches to WB to be a true 1/8 scale, but buy tooking at the Required Track Width it is sitting at 1/8 scale. Regs say 93 inch TW divided by 8 is 11.6 inches which is about right. I think by these standard if Traxxas would have used the Platnum chassis it would qualify as 1/8 scale. Now all this is in respect to WB an TW and accual body size hasn't been considered here.