I have absolutely no experience with the stuff, but there are products out there to let you print your own inkjet waterslide decals.
They key for successful printing (so I am told) is the special "inkjet bonding agent" included with the kit (the kit usually has a spray can of the bonding agent and a few white decal sheets and a few clear decal sheets).
This bonding agent allows the inkjet ink to stick to the sheet and dry, a second coating seals the sheet and prevents the image from dissolving when you place the decal in water for application...
You could always try the bonding agent on styrene, I think Testors sells it separate from the kit.
Allegedly (again, so I am told), Krylon clear spray will accomplish the same thing.
This is the Testors spray:
https://www.hobbylobby.com/Crafts-Ho...l-Spray/p/1157
You might try scuffing the plastic with
very fine steel wool prior to printing to give the plastic some "tooth" for the ink to stick to.
Don't know if you have "overhead transparency" as a print setting or not, you might try that. (Although, usually transparencies that you could print on were specifically manufactured as such, and does anyone actually use overhead projectors any more?)
One thing that has been on my "someday I'll try that" list for a long time is to try laser printing onto the backing paper from adhesive labels,
carefully placing plastic on top of this, and then running the whole thing through a laminator to fuse the toner to the plastic. (I have used something called toner reactive foil in the past if you're wondering how the heck I ever came up with the idea.)
Having said all that, if you want something to put R/C gear in and use as an actual watercraft, why not look into waterproofing the paper model once it's built?