Installed Alm. A-frame motor mount will have to put new wood on back would 3/4 in. marine grade plywood (two pieces glued together,1 1/2in. total, then painted and with alm. bolted around edge work o. k. Also would using same plywood for deck on galv. stringers be o. k. When mounting motor how deep must motor be, water line at or just above first fin above gear case or must water pump be under water. Fresh water use only and with tilt and trim. Thanks for any help.