bolting square aluminum without crushing walls

[greencactus3]

we're gonna use .125in wall square 1x1in aluminum for some things this year. and were wondering about if you wanted to say.. bolt a pillow block to one face of the aluminum. so, drill a hole through the whole thing. as in 2 opposing walls. and then bolt goes through the pillow and then the whole alumiunm.. through 2 walls with space between. gets a nut on the other side of the aluminum.
if we crank down on the bolt, the walls of the alumiunm get crushed. how do we do this without crushing? not cranking as hard might not be a good idea as we dont want axles wobbling around.
and drilling a massive hole on one side of the alumiunm so we can fit a nut through that is an option but will take away structure from the square, as 1in sides means a lot of surface area taken away.
anytips from the veteran teams? btw our pillows are steel or zinc or sumthing. not aluminum so welding that on would be complicated. if possible,. i dunno