Secret fixings

[KTMMICK]

Yeah, thats what i'm thinking

Can you use Chem fix.......not sure if that is what you mean by resin anchors!
Excuse my ignorance......but I would do as you say and drill the top to take a socket then fix just through the bottom, it will save you sleeving the RHS also.

When I was in UK we used to fix nearly everything down with that and now I am here in South Africa I use it to fix Balustrades down, weld studding on bottom of posts, drill hole fill it up and slot in.....they never move.
http://www.fischer.co.uk/desktopdefault.aspx/tabid-1777/1361_read-2282/ I have trolled the net and found this.........get the SE to speak to the technical department at Fischer and he will be able to advise.....you can get countersunk nuts but I have been struggling to find them. And my mind has gone a blank on suppliers we used.

 

[Hitch]

That is chemfix that we are on about Mick

 

[KTMMICK]

Thank you..........was not sure, I have never had any bother with it myself you see. If you can source countersunk nuts job done.......I would go that route myself first and if that fails look into the hole big enough for a socket and blenk it off afterwards.