Perhaps a good case for a Voyager or Tow Pac Insta Trike. It's not a permanent conversion and can be removed in a few minutes if you want to take the bike in for service work. On the Tow Pac only adds 150 pounds. They provide the stability you need at a fraction of the cost. New, cost 4-5k. Bought mine used in like new condition for 2k.
2003 Honda Silverwing
2005 Honda CB 900f 919 Hornet (Hercules)
2007 Suzuki Burgman 650 (a real man's scooter)
1995 GL 1500 Aspencade (sold)
1985 GL 1200 LTD (sold)