I used wire tie's most come with some sort of tie

i have a pair of thro overs.converted to "hard" mount..
theyre river road slant style,came with plastic  that runs inside up the front and back and across the bottom(helps in shape retention) used cardboard to trace the back  after a few trys got it to fit just so then taped it to a double sheet(one for each bag) of 1/8" plywood ,jig sawed and sanded to fit ..used 3/8" 1 hole conduit (squeezed to fit)straps, washers,screws and nuts to attach to saddle bag bars ,works great i have yokes tucked and tyed down out of the way..thinking about cutting them off