We went kayaking in a lake somewhere in Michigan, I can't remember which lake (we've been to hundreds). They had a steep incline about 100 ft down (around 20-25 degrees) down to the lake. The hill was grass covered. Getting the kayaks down there was no problem, so we went for it, and launched hoping while we were out we might spot a better place to take the kayaks back out (we had a Revo 13 and an Oasis (pretty heavy). Well long story short we never found a better way out, so we had to get the kayaks back up the hill.
We ended taking the wheels off the kayaks and pulling them up the hill with the anchor line tied to the bow, and to the back of the car, then drove the car 100 ft forward, it worked great, and we didn't have to buy anything. I suppose if it wasn't grass we could have put a blanket under the boat to protect it from rocks, but hey it worked just fine.
Also when we are at Florida beaches with super fine white sand (like Siesta Key Beach or Lido beach), it is nearly impossible to drag our kayaks thru the powder soft sand with any type of wheels, we have tried the wheel-eez grey air filled tires, and it is still extremely difficult in this super soft sand. What I do is remove the wheels and with one on each side we just drag the kayak thru the soft sand. It's actually easier to just drag the kayak than trying to pull with any type of wheels especially thru beach grass.
We have had 7 or 8 Hobies now, when we had the first few we were very careful about not wanting to scratch the bottoms, anymore, the bottom of the boat is the least of our worries, they are going to get scratched up, I don't worry about it, I just have fun. I honestly cannot tell any difference in speed with a clean bottom or scratched bottom, if there is a difference, I can't tell.
I do try to clean up the bottoms once or twice a year, they are pretty easy to clean up, and if you have one of those Hobie plastic welders (available from Hobie, and not very expensive) just repair the big gouges, and don't worry too much about the rest. The hull bottoms are as much as 3/8 of an inch thick in some places, and in a lifetime you are not going to wear thru them.
If I were to pull my Hobie up a steep incline, I would definitely remove the scupper cart, and just drag the hull up with my car on the anchor line, but that's just me. ( I have wrecked several hulls with those stupid scupper carts)
But then again that's just us.