Is this safe?

I am another that isn't afrade to run a little over, but that is 700lbs plus the people /pets inside and anything else you put in the truck and does you wet hitch weight include the weight of the 5th wheel hitch?  in reality you probably would have that truck overloaded 1200 to 1500 lbs when all is said and done as the factory listed hitch weights are never right.  for example mine was listed at 2200lbs it came in at 2950lbs.  also when they say loaded, that is probably on a base modle with no options whats so ever and loaded with what, do they have any extra batteries in the front compartment and so on......  take thoes with a grain of salt from the manufacture they are are lighter then they end up being.  

Like Grit_dog, I do not claim to be among the weight cops. But I quite agree with him on this one. That is a capable truck, but the trailer is too much for it, especially as equipped, but I suspect regardless of mods you might make. You are not merely 700 lbs over payload, you are 700 lbs PLUS THE WEIGHT OF PASSENGERS and any other "stuff" you might have on board. Assuming just mom & pop, no kiddos, you are looking at 1100 lbs over, probably more. The towing experience will suck bigly, especially for an inexperienced driver, and yes, it will eventually damage the truck, and yes, probably unsafe, and might indeed cause issues with insurance, should (heaven forbid) there be an accident.

I highly recommend going with a trailer within the capacity of the truck. Remember, trailer sales people routinely lie that a customer's truck can handle a given trailer. They care only about making the sale, not about the customer's experience later. So much so, that there is a dark joke about it: Do you know how to tell if a sales person it lying? Their lips are moving.

On second thought, sell the truck and buy a timeshare. 

I’m far from being an internet weight cop and with that said, you will be right at the practical limits of a srw truck and of course well over payload rating. 
A few things to consider. This being your first camper and your inexperience at towing much less towing basically a semi trailer, and your perceived lack of understanding, it sounds like a horrible idea from here. 
17” wheels = base model truck and the tires are surely not up to that weight rating. At a minimum I’d be somewhere between some heavy rated 18s or 20s rims and appropriately rated tires. Or 19.5s. 
If you’re experienced, equip the truck right and keeper out of the mountains it’s semi reasonably doable imo. But not with how the truck is currently equipped. 
And I with more knowledge and experience wouldn’t even want to tow that thing with that truck on any significant grades or curves.