Upgrading a SRW with heavier suspension and 19.5" wheels will safely give you a 9000 lb rear axle rating, but you're looking at about $4k or more in upgrades that could have paid for a DRW. So yes, it is possible to safely tow something large with a SRW. If I already owned a reliable SRW truck and wanted a FW with more than 3000 lbs pin weight, I would consider spending the money to upgrade. If I was looking to buy a truck, I would be scaling it for something larger than I currently want tow to give me choices later (that means DRW). If I was adamant about keeping a SRW for daily driving, going to 19.5's is your only option for pulling something that heavy.