700Rs are junk! Why waste the money! Right?
Yeah, and notice my comment below yours, I am going to spend $650-$700 in upgrades to TRY and build a stand up unit. And it'lll be a test unit for abuse. For real, noone is giving you bad info. I'd say go for the 700r4 in a half ton daily driver, but that's about it. Past that, unless you know how to build transmissions and do it often, I'd avoid it for your 3/4 ton. The 4.10 gears are good for it, and the stock OE tire that you're running is good for it too. But you mentioned the dreaded word, "TOWING".
89S Tows his boat with his Burb and 700r4. He doesn't use OD and only tows it couple miles from his house to where he docks and probably doesn't get over 40mph.