I'd also go Nelson (even over Dunne). Normally wouldn't advocate but need as many CBs in the team as possible against this mob. Tony Pulis style back 4 of CBs.
Can't seem him changing to 3 at the back. What do you do ahead of that? Who plays wingback on the right? I guess you could play a Bielsa style 3331 with a narrow midfield of Smith, TD and Doughty.
I would go with Nelson at RB but if he did go for 3 at the back (which did the trick last season if it wasn't for the stupid sending off of Preston) then I would play McGlashan as right wingback, hes good at tracking back and made 2 good tackles on Saturday and a couple vs Chelsea too, even though its not his natural game he would have cover from the 3 CB's if he didnt tackle his man.
Lincoln also play with wingbacks that get forward not normally with wingers, so instead of facing 2 players attacking him it would just be 1, Toffolo. If McGlashan attacks his man then Toffolo wouldn't have the chance to break forward much either.