Yes you can do that wall splash trick. Even works on Town claims that have stupid builds.
That is why I recommend you have several grid areas with their own set of walls and braziers. That extra 5 tile gap (should actually be 6) will end up costing quite a bit of silver that you should probably have invested a town claim anyways. As long as your wall is stone on the perimiter most raiders are not going to go thru the trouble of transferring in lime granite and stone to wall splash bug abuse. You guys have no idea how overpowered braziers are. As long as you have not pissed off titans, even a dozen braziers in a small claim will deter almost all raiders. Stick to my recommendation on # of my braziers as bare minimum (even easier now with the circle radius showing up on brazier construction) to have adequate brazier coverage. Even seasoned raiders 300+ biles are not going to 'inspect' your claim with 2-3 braziers covering any area.
At this point in the game it's not even worth the raid food as a Raider to bother with claims that have braziers unless they are a target.