I think mounting the seat to the mini bracket may be a bit hard seeing as they are completely different. You most probably will need at least a customized bracket between the mini mount and the excel mounting point, this will be the item that needs to be approved, if you understand what I mean. Also how are you mounting the rear of the seat
again that will need approval 
Good luck with it all though.
P.S. This topic should probably have been put in "mini chat" seeing as it is not a question about A or A+ engines, you will probably get more responses in mini chat as well