My husband and I have been a avid DIYers for a long time and have done many projects around the house, but we have searched for repalcement bench slats for my 2 wrought iron benches for some time without finding good strong hardwood to replace the molded and deteriorating slats that came with the benches. Most wood recommended at the stores are too sofe and will sag without a center support, which I do not have. What do you suggest?