Pulling doubles with a 5er is easy and more forgiving than a bumper pull. Pulling doubles with a bumper pull is also possible but you MUST get the tongue weights and balance perfect or you will sway. Once a double bumper pull starts to sway, you are in trouble. Personally, I used a sway control on the rear trailer just in case. Probably didn't need it but even if I tried to "test force" a sway, it always made the 2nd trailer go back straight. My BIL pulls double bumper pulls and has no issues.
In either case, you cannot see the 2nd trailer unless you have a camera. I have personally seen someone dragging a flat on the second trailer without knowing and another dragging the 2nd trailer by the safety chains without knowing.
Also, you need to mind state laws. Most limit total length between 60 and 75 feet, require brakes on the 2nd trailer and some don't even allow 2 trailers. Some states require the safety chains from the 2nd trailer be attached directly to the 1st trailer's frame. For instance, Utah is 65' (100' with a permit) and requires brakes on the 2nd trailer if it is over 3,000 lbs. I was about 72', chains to the frame and no brakes on the second trailer and never got questioned in Utah. Went to Sand Hollow and back, passed a dozen HP troopers and not one of them pulled me over. Pulled through several other states and never got questioned either and I doubt I was 100% legal in any of the states I drove in.
Not sure about where you are located but here in the west, if you are driving the speed limit and staying in your lane, it seems the HP have better thing to do with their time here.
If you decide to tow doubles, I highly recommend a backup camera on the first trailer and TPMS on all tires.