So many options for a Class "A", Class "C", Truck with Trailer, etc., etc. etc.

Truck and trailer wasn't an option, because I wanted to have the option to bring; (2) Quads, (2) Jet Skis, or (2) Mopeds.

However, I didn't think it was legal, but I saw a Truck, 5th Wheel Trailer, and Trailer combo. If registered in home state, is it legal to travel across another state.

Jack

Each state is different. Also might need to watch "total length". Maybe someone lese will chime in who knows more.

Larry is correct.
Some states allow it, some don't.
Some have restrictions on what you can tow behind your 5er.
Most if not all states that do allow it will have some kind of overall length limits.
What is legal in one state does not mean it will be legal in another.
Statutes concerning double towing is like nearly every other statute - they are state specific. What one state allows has no bearing on what another state allows.
Do not rely on statutes for commercial vehicles. Many if not all states will have separate statute covering RVs/non-commercial. What may be allowed for a commercial vehicle will not be allowed for RV.
Be careful who you ask and who you believe. Some people know but a lot don't. Too many rely on internet stories they've heard from someone else who doesn't have a clue either. Or they will cite some internet site that is put together by who knows whomever. There are some websites that have some major erroneous information.
If someone actually knows or says they do then tell them to provide the applicable statutes for their state. You'll find alot of people have never read a statute nor have any idea where to look.
For IL here is what the statute says:
(625 ILCS 5/15‑107)
Sec. 15‑107. Length of vehicles.
(c) Except as provided in subsections (c‑1) and (c‑2){refers to semi truck/trailr combos}, combinations of vehicles may not exceed a total of 2 vehicles except the following:
(5) Recreational vehicles consisting of 3 vehicles, provided the following:
(A) The total overall dimension does not exceed 60 feet.
(B.) The towing vehicle is a properly registered vehicle capable of towing another vehicle using a fifth‑wheel type assembly.
(C) The second vehicle in the combination of vehicles is a recreational vehicle that is towed by a fifth‑wheel assembly. This vehicle must be properly registered and must be equipped with brakes, regardless of weight.
(D) The third vehicle must be the lightest of the 3 vehicles and be a trailer or semitrailer designed or used for transporting a boat, all‑terrain vehicle, personal watercraft, or motorcycle.
(E) The towed vehicles may be only for the use of the operator of the towing vehicle.
(F) All vehicles must be properly equipped with operating brakes and safety equipment required by this Code, except the additional brake requirement in subdivision (C) of this subparagraph (5).

Hey larry that would be good info to add to the website.