I have a three tier (6, 8, 10 inch) mudcake wedding cake coming up. Bride is deciding between a "naked" look cake and a messy look buttercream finish.

Other info... Australian late Spring, so quite warm and probably humid. Buttercream will be butter based rather than shortening based. No separator plates - tiers on top of each other.

Normally I'd stack the bottom two tiers and assemble the third onsite, but this cake will be travelling a solid 2 hour trip, not on the best roads and I won't be there to assemble. Being worried about that trip, I'm considering doing a dummy tier or two if the bride goes with buttercream finish (not possible on the naked cake unfortunately, so not sure what to do if she chooses that!) 

Question is... Will styrofoam dummy cakes hold buttercream? I haven't tried it before.

Failing that...suggestions on the best stability mode apart from hard-core doweling? I'm thinking lots of pre-chilling and air-con pumping!

Thanks :)