Aye, lad - looks like you'll just have to do it the hard way like us had to in the Old Days before all this mamby-pamby symbolic debugging came along.
Things were hard back then, but we were 'appy!

http://www.hellas89.new.labour.org.uk/page8.htm

Seriously, if you don't have symbolic debug for structures, you'll just have to work out the member addresses by hand.

I suggest you set up an Excel (or whatever) spreadsheet with all the member offsets in, so then you can just put in the structure start address from your Linker map file and let Excel do the donkey-work of calculating all the individual member start addresses.
Well, that's what I've done in the past with similarly limited tools!