5g buckets foull of concret have worked for me.. or you can custom cast yer own concrete hanger weights using some fence wire, and bolts,a nd easy to make concrete forms ( old drums or buckets or pans, styrofoam.. etc.. etc..
i made some for the front of my 4600 ford. once cast and cured.. a lil black paint made em look almost like cast iron weights from a few feet away. cost was super cheap.. just some scrap wire and bolts for mounting, and bags of 'crete.
used old big feed pan as a form, and some cooking pan coating as a release agent..
soundguy