Wanted to recommend the Camco Rhino Tote Tank. Really like the new 4 wheel version. Just seems really well designed and constructed. The 28 gallon is just a little bit high to go under my Forester but it worked great. Still a stinky job but easier thanpacking up and driving to the dump station.
In the future I hope to drain when half full so it only takes one trip. Don’t really plan to tow with the bike either. Wasn’t too bad but sure wouldn’t want to go up hill!