Other than to give them another opportunity to try and talk me out of a HBAC? Judging from the UK homebirth group the general concept is to find reasons why your house is unsuitable.
Ironically we don't want to have the baby in the house, we are planning to use the studio next door, big room, easily temperature controlled, double doored access (for ambulance etc. in emergency) single level bathroom, disabled access etc, beds/birthpool can be installed and still bags of room, controllable lights, it's ideal. It'll just freak them out because at the end of the day it's a recording studio (complete with grand piano in the corner).
I plan to use the 'now hang on, wasn't Jesus, apparently, born in a stable'. argument, in any case. Ho hum.