i know that this can't be a full solution (and I haven't seen a screenshot of those grids) but at least having buttons on the left side should work better..... did you try with button_placement = 'left' ?
also, for bootstrap customization, can't it be achieved using the ui dict ?
PS: if you can came up with a "proof of concept" (even a screenshot) it may help to code that into SQLFORM.grid directly.