I would suggest using the Trik-L-Start since it is the only product that uses your RV's existing charging system to keep the chassis battery charged.
Not so - the Xantrex Echo Charge does that as well.
I'm kind of surprised your Bounder doesn't charge the chassis battery from shore power on its own - all later Fleetwood RVs do so. Not sure if they had added the charge controller yet in 1987, but I thought so. Maybe yours isn't working right. Even so, it may be easier/cheaper to add the Trik-L-Start or Echo Charge than to find and fix the problem.
You could also add any decent portable automotive charger and simply plug it in, either to the coach 120v system or an external extension cord when at home. Most modern car battery chargers have a decent float charge mode.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL