Have you towed before?
If not, I think you ARE in for a HUGE learning curve with a 35ft trailer or even a 27 ft trailer..
If you are totally new to RV camping and have never towed before, perhaps it would be better to rent a RV for a one off trip to see if:
#1 you like it
#2 your boys like it
#3 you are OK will ALL of the setup, tear down, towing and maintenance of said RV.
Takes a lot of WORK to RV camp..
I have been to a bunch of places around SC when I was a kid yrs ago, lot of nice State Parks, but many of those do not have full hookups so you need to factor in having to get fresh water, get rid of grey and black water.
Now days we just go to the SC beaches with full hookups..
No matter how you cut it, buying a new or even used trailer then adding in the expense of a used Eco or Diesel vehicle for you first time could amount to a extremely expensive mistake if you find that RV camping turns out not anything your family likes..