Oh hey, so you meant that Stinger. Wasn't sure if you meant the one used in Battlebots or the Robot Wars one.
What armor does this have?
In case you don't know, in early stages the game used to have armors that had double the HP of what the current ones have. All AI bots use such armor and if you don't touch the armor tab you get double stenght aluminium(DSA) which is stronger than steel and weights just as much as normal aluminum.
People usually only use Shiny Hub Wheels(they're the lightest) and rubber wheels(give you zero ground clearance with HP motors), if you have leftover weight or need them for strange designs, then feel free to use the other wheels.
Not sure how much use that weapon on the back has, think it would be better to just make one weapon and place a T connector on it, together with 20 cm extenders you should be able to put 4 razors on there, now that will really pack a punch.
In case you wonder how to attach them, here's a little help:
RR RR
EXTEX
P
R=Razor
EX=20cm Extender rotated to have the attachment points forward
T=T connector
P=Piston.
Like already mentioned by other users, you can make the chassis smaller which should allow you to put on smaller wheels and more weapons. The battery should be more than enough(given that it's only needed for the drive), might want to downgrade that. Not sure how much air that Co2 canister gives but once you reach about half your weapons will start to lose power(still think it's enough for a LW).
Maybe you can get enough weight to even increase the drive motors to normal Zteks. Try to keep them in this wide position like now, because more distance means better turning(where it's the opposite in real life), so you probably want to have a chassis that's T shaped(just like the Stock AI Stinger, except the other way around).
As for back weapons, most matches in Robot Arena 2 are 1vs1 and the AI'd robots(you will probably learn how to AI bots later) only attack front on front and don't drive to the back of a bot, that's why people usually only put stuff on the front. Imagine it like those anti spinner wedges you've seen in Battlebots, Front and a bit of side.