Botulism (along with any other pathogenic organism) isn't an issue with beer because the pH and alcohol kill will it, so no worries there. Lacto will be killed by a 15 min boil. I've had good luck with a hopped mash, decoction, and just heating the beer up to ~210 before chilling/pitching a slurry of lacto and Sacch. Just make sure you keep the IBUs really low.
I use carboys for sours and clean beers and have only had an issue one or two times. A long soak in hot water and Oxyclean/TSP/PBW etc... followed by a long soak with Star-San for the carboy seems to keep my clean beers clean. I have two sets of post cooling equipment otherwise though (tubing, siphon, bottling wands etc...).