Don’t have any plans but I built a trailer for my sled a couple of years ago. The reason I built my own is there are not many available the way I wanted it to be.
If you want an inexpensive 2 place I suspect a used commercial one would be cheaper than trying to build your own. Perhaps one that needs some rebuilding would lower the cost and offer the opportunity for customizing.
I wanted a small, light, single place tilt I could tuck in behind a compact car. I started with an axle and springs from an old tent camper. Built my own shackles, frame, deck, and tongue.
Been using it a couple of years now and it works great. Tucks in nice behind a compact car and tows great. I use one of those covers that extend out over the ski tips, but most of the splash from the tires just goes past the sled. For extra slushy roads I did build small removable deflectors to protect the outer edges of the trailer from accumulating slush.
I also installed one of those gas prop rods to help hold the empty deck in the upright position for one-person drive on loading. Works great!
Four 2x4s angle cut at the rear make a great way to center the sled. The 2x4s are spaced far enough apart to keep the skis up and prevent the carbides from touching (and damaging) the deck. I don’t use studs so no deck protection was needed in the rear of the deck.
Below are a few photos, hope this helps.