It's not a good idea to do this since the stall charactaristics would be different upright to inverted.

If there is a stall/spin sensitivity that the pilot can't live with the proper solution for this type of plane is to use outer placed turbulator strips, root stall strips, reshape the leading edge to promote an earlier root stall, or build a new model with a tip airfoil that slightly delays the stall. For example moving the max thickness point further forward often helps unless its a forward high pont already. The leading edge shape can often play a big part too. A sharper nose wanting to stall earlier if all else is equal.