If the E-Z-LOADER trailer is in good condition, you certainly can convert it to a keel roller trailer with bunks.
As for trying to reuse some mounting components from the floppy rollers, it may be simpler to just buy the appropriate bunk mounting brackets. For two bunks you will only need four mounting brackets, so the cost should not be excessive.
Using 4 x 6 lumber for the bunks for a relatively light 16-foot hull may be a bit excessive.
Having a multitude of keel rollers on which the entire weight of the hull is to be carried is not an absolute requirement. A mix of keel rollers and bunks is entirely suitable for supporting a Unibond hull.
On my own trailer (which is also an E-Z-LOADER from 1992 and whose galvanized steel is still in excellent shape), I use two pivoting bunk sets of two-bunks (for a total of four bunks) to support the aft half of the hull, while two sets of paired keel rollers support the keel in the forward half of the hull. The boat spends about 99-percent of its life sitting on that trailer, and there is no indication that any any harm has occurred.
The keel rollers are very useful for loading the boat onto the trailer on a sloping launch ramp, as they will be the first point of contact between the hull and the trailer as the boat is pulled up and onto the trailer.
Your particular E-Z-LOADER trailer has curved crossmembers on the trailer frame. You can still use keel rollers, but you will probably need to use one-piece mounting brackest.
The general goal in the rigging of the trailer is to carry the hull as low on the trailer as possible. There are two factors which will determine how low the hull can be situated:
- the clearance between the hull and the trailer fenders; if your trailer is wide enough, it may be possible for the entire hull to lie between the fenders, but otherwise the chine line of the hull should be above the fender tops by about 1-inch; and
- the distance the keel rollers can be positioned above the trailer crossmembers; in some cases the lower mounting bolts for the keel roller one-piece mounting brackets can go through the crossmember. See Figure 2 (below).
- Fig. 2. Paired keel rollers installed on trailer. In this view the brackets are mounted as low as possible to the crossmember.
- pairedKeelRollers.jpeg (117.06 KiB) Viewed 516 times
While using paired keel rollers for a 16-footer might be excessive, mounting two keel roller brackets back-to-back will actually simplify the installation.
Note above in Figure 2 that in some situations the lower mounting bolts may need to pass through the trailer crossmember. This occurs when a higher roller position is desired. In that instance the holes for those bolts must be located on the exact centerline of the vertical face of the crossmember in order to minimize loss of strength in the crossmember. Be sure to use a galvanizing spray-on compound to restore rust protection for the steel at the drilled hole, before installing the brackets.