75% speed drop from RV to trailer?

So I just got the Ultimate Road Warrior VR2 Internet Bundle. I got a 30 foot RV towing a car hauler that has a small office in the front half of the trailer that I work out of, wife works in the RV.

The speed in the RV is right on my minimum requirement. WIFI in the car hauler is 10% of what I get in the RV. Ran a hard line, unfortunately 250 foot (CAT 6) in the shortest I have on hand and that only gave me 25% the speed I have in the RV. I’m not sure if I bought a 50 foot line it would make that much difference.

Not sure the best, cost effective way to get the same speeds in the trailer as I am in the RV.

Any suggestions?