Charles,
Regardless of the trailer you decide to get, make sure you pay attention to the gross weights and gross combinations to ensure you comply with your local laws.
From what I can tell (after hours of reading and talking to the different authorities for my state, NJ), it really boils down to this:
-You can basically have whatever trailer you want; HOWEVER, you just might need a CDL and/or a USDOT number to pull it about.
My understanding is that the states are supposed to copy the federal CDL standards. Some states interpret these differently, and it can be REALLY confusing. Some states say you need a CDL if your trailer is greater than 10K GVW...regardless of the GVW of the truck. Others say the 10K rule only applies when your combined gross weight of truck and trailer exceed 26K (like NJ).
Here's the best part! The laws are so **** confusing that we spend hours debating them online and nobody knows for sure what's allowed or not! Not even the COPS! It's really a joke. For example, NJ is made up of something like 566 municipalities, most of which have their own police depts, 21 counties, most of which have their own sheriffs depts., and the NJ state police. So, in my town 3 different sets of cops can write me up for a moving violation....and I've called them all and got DIFFERENT answers about the rules!
The answer I chose to go by was from the NJ State police division that actually sets up checkpoints to weigh trucks. They say if your combined GROSS weight of truck and trailer exceeds 26k, you need a CDL. It doesn't matter if the trailer is 20k GVW and the truck is 6K, or if the truck is 20K and the trailer is 6K, once you break 26K in combination, you need a CDL. This gets more complicated when you factor in that NJ cares more about how the truck is REGISTERED with the state rather than what the stickers really say! And, if you use the truck commercially, you have to register it differently. Anyway, that's just NJ.
My point in saying all this, be careful when crossing state lines. Make sure you're legal in the state you're going through, not just the state you live in.
Regarding the
M59, I would bet that you need a CDL to pull an
M59 around in most states, because any trailer that can do it will need to be over 10K GVW.
Lowboy vs. deckover...I think that depends on how often you will side load the trailer. The wheel wells do get in the way, but you can usually work around them or put some big pressure treated wood stock in the middle to raise up the deck. When it comes to loading equipment or vehicles, I like having the low deck much better than a deckover. Overall, I vote for lowboy.