a few things come to mind here, as to how clean or dirty it wikll get
as the SIZE of the truck matters here, is it a full sized truck or mid sized,
8 ft bed or 6.4 or smaller
how far are you hauling it, and in what type of roads and traffic conditions
as all that changes things
a truck that sit taller will get less slop on truck as it gets higher(normally where does salt slush build up< the lower end of the vehicle and the front and back, the roof doesn;'t get a lot , if you follow)
so a sled in the back of a tall sitting truck will protect it better than a lower riding truck
next, the size of bed matters,a s again, the very BACK of a vehicle will collect salt and slush, so, if there is more sled in the truck and less on the tailgate, it will stay cleaner
and then, HOW far and fast are you hauling it and will it be on back roads , or highways?
short trips or long hauls?
short hauls on low traffic roads, things will stay a lot cleaner, than the rest!
more vehicles on the road and faster they are going, the more salt mist and dust will be in the air, and that will lead to landing and sticking to things
and if your on very LONG trips, and encounter things like rain or wet snow, things can freeze to a bed of a truck, making unloading a pain in the ass deal!
so it all matters
and then, adding a cover
YUP will sure help keep sled clean, but can be a real pain the ass to add to sled in a bed of a truck(been there done that)
how young and agile are you?
for em the hassle of hauling a trailer is worth the added, benefits, cleaner sled, faster easier loading and unloading, and less wear and tear on the sled in the long run!
butthat is, a personal deal,