Its been a while since I hauled a squirt boom but don't most of them steer with the rear wheels when in "normal" mode? If you get the front wheels straight then you just steer the back. I just line up as I drive on the trailer never worried about the axles being perfect, the biggest squirt boom I ever hauled (15,000#) was still less than 8'6" wide so it was easy to line up on the trailer. If you need the front end over I just turn it to roundhouse, turn the front wheels the direction I want them to go, turn it back to rear steer only, move ahead until the front is where I want it then correct the rear wheels the same way. You can look back and get the wheels pretty straight. If you use the other trick I posted in my last post while your driving it around you can tell if your straight.
It's been a while I guess, we rented a 10,000# Cat this year (which is just a rebadged JLG) for a small job, I think you could run it in rear steer only but I'm a little fuzzy. Still squaring up and 8' wide machine on an 8'6" trailer isn't to bad.
Any Cat/JLG I've seen is front/crab/4 wheel steer. A guy can eyeball the back axle pretty good from the cab.
These suck to operate. Electronically controlled to the point of being garbage. If you don't hold your tongue right, plant your left butt cheek into the proper spot on the seat and move the controls at the exact, precise speed they won't work. I absolutely despise anything built by this company.
I fully admit I could and probably am wrong about the steering, I used to work for a company that rented most of the brands and hauled them regularly but in the last 6 years I've hauled 2 so I'm out of my element and I yeild to experience. Either way they are pretty easy to load.
Why, because they're designed for people who give up? My favorite part about loading/using heavy equipment is watching my oldest friend insist he's saving fuel by always running at low idle on any machine; and stalling it 75 times whenever he tries to do anything. I don't do much machine moving, nothing even large when I do: fun to figure out how to use a new tool.