Weight question

Hello All!
I scoured the web on cargo conversions and found almost nothing until I located this wonderful section. Partially due to not understanding how to calculate my towing capabilities and the remainder of not knowing how much an average build would add to my total, I am not sure what I will be able to safely tow.
Although I can understand the weight will have a huge variance baesd on materials and additions, I am just looking for some examples of what people have and use to tow it with. I have 2 different vehicles that will do the primary pulling. Both are SUVs with one being a Yukon and other Grand Cherokee Limited - Yukon has the 5.3 and Jeep the 5.7 Hemi. They are rated at GVWR 6600 and 7600 if I am not mistaken. I'm a little fuzzy on what that means.
Basically, what would be a good size for me to safely convert? I was thinking 6x12.
Thanks.
I scoured the web on cargo conversions and found almost nothing until I located this wonderful section. Partially due to not understanding how to calculate my towing capabilities and the remainder of not knowing how much an average build would add to my total, I am not sure what I will be able to safely tow.
Although I can understand the weight will have a huge variance baesd on materials and additions, I am just looking for some examples of what people have and use to tow it with. I have 2 different vehicles that will do the primary pulling. Both are SUVs with one being a Yukon and other Grand Cherokee Limited - Yukon has the 5.3 and Jeep the 5.7 Hemi. They are rated at GVWR 6600 and 7600 if I am not mistaken. I'm a little fuzzy on what that means.
Basically, what would be a good size for me to safely convert? I was thinking 6x12.
Thanks.