Since your
boat has an external hull-to-deck joint your
project is, in a word, cake. It is a little hard to tell from your pictures, but it looks like your toe rail is attached with 1/4" carriage bolts. To confirm this remove one and have a look. Now measure the spacing between the holes, and the distance from the holes to the edge of the deck.
Call the toe rail company and ask whether the bolt holes are punched square or round, and give them your measurements. All ok? Then order what you need and skip the next paragraph.
If your hole spacing is uneven, or the company cannot provide toe rail with the holes the correct distance from your hull-to-deck joint, or ___, then see if you can get toe rail that has not been pre-drilled and drill the holes yourself - aluminum drills very easily. Then use pan or round
head machine screws, either 18-8 or 316
stainless steel should
work for this application.
Remove and replace your old toe rail one section at a time - remember the bolts through it are holding your
hull and deck together. Remove the bolts, if bedded with polysulfide the toe rail should come off with a little effort, but it may not have any bedding at all. Clean the area. Start attaching your new toe rail at the curviest part of the hull first (i.e., start in the center and work forward) and just "worry it around" the curve of the hull (tie a
rope to the front of it and attach it to a cleat or something on the other side to pull it around) and (if necessary drill the holes and) bolt as you go.
Since your hull-to-deck joint is external, although it is preferable, it isn't required to use a bedding compound. You can try, but it will be messy. I just looked at the Hunter next to me and their toe rail is bolted with countersunk flat
head screws. I couldn't tell if there is any bedding compound or not because they have run a big bead of silicon along the toe rail-deck joint.
Also, after you get done, if you haven't exchanged the dog for a cat yet, cut a few slots in strategic locations for the urine to go
overboard. If you run a bead of
sealant along the deck joint that will keep the urine from getting under the toe rail and get you a few more years before you have to do this again.
Your quote seems expensive - I have removed my aluminum toe rails and am replacing them with
teak, which is costing me much less than that.