On our 4500 I put 1/2 inch plastic drip irrigation line over all the copper tubing. I just took a utility knife and cut the plastic the full lengthen to cover each section and then just spread it apart and slipped it over the copper line. When I cut it the length of it I didn't worry about cutting it in a straight line as if you go crocked when cutting it when you install it, it won't have the split running in such a way to come off of the copper. No need to put any tie wraps or any thing to hold it on as it is heat molded round and that's the way it wants to stay. I have had it on our 4500 for 9 years and over 65,000 mile with no problems. Yes lot's of hiway miles but lot of time outback.
My only worry was we use it for boon docking in the Mojave desert and rocks scraping against it or one flying up and putting a hole in it. It hasn't happened yet.
I also had the axle
replaced 2 summers ago while in Sault, Michigan at Soo Welding shop that does trailer mods and hitches for over 50 year. I highly recommend this shop, my family has used them for any welding tasks that are out of our league. I wish they were in California where I live now as I am always building stuff. They put on a 3500 lb axle
and set is so it raised the Trillium
up an extra 3 inches for more ground clearance and they replaced the 1 7/8 hitch coupler with a 2 inch one and everything was $600 installed, they supplied everything. This shop knows what they are doing and don't try to beat you up on high prices. They had to order the axle
and it was there in one day and they called me to drop off the trillium next morning. I took it in when they opened about 8 am and they called me at 2 pm same day and it was done. I went to pick it up and the job was better than I though it would be, nice quality welds and no burn spots on the fiberglass. He said the rest of the frame still looked good, it is a 1980 4500 trillium that lived it life, 36 years in California climate so no rust issues.
I had him save me the old electric brake setup to use on a utility trailer I have at home that needs brakes
to feel safer in the mountains where I live.
The Irrigation line is available at Home Depot. I also use it as a conduit to run electrical
wires along the frame on my tow vehicle as well as on the Trillium. It keeps them from getting scraped up or cut.