Do you already own a Brake Buddy? I ask because we have owned two. Both have worked well and been pretty reliable. Company also offers good tech support. We got ours back when there were less choices than there are now, and we had two vehicles we could use as toads. Those two are gone but we have two more that we cam also use as toads. So, for us, we're invested in only one braking system and that's good.
BUT!!! The In and Out with a BB isn't all that difficult, but it is definitely NOT convenient. For One Toad for One Coach, I'd be looking for something that stays in place. I think BB might even offer one, called Stealth. I have NOT looked into it.
Next, check compatibility. I can't define "active braking" that some late model cars have, but it can affect which braking systems will work.
I found
This on a Cadillac Forum and it might help you. But I think it's an earlier SRX.
Notice what they write about pulling fuses and about a direct power connection for the BB. Ever since cars went from high amperage "Lighter Sockets" to low amperage "Power Outlets" BB has seen problems in operation of their units. They therefore sell a Kit to go straight from Battery to a METAL socket for BB to plug into. If you call Tech Support they will send you one free. If you in fact go BB, run that power source along with your Breakaway line.
Can't help with where to pierce the firewall. I've always been able to find a grommet of some kind I could poke a hole through. Just make sure both sides are clear!
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB