Lots of good advice above!
I have a Dutchmen Kodiak Cub, 21 foot TT. The manual specifies one additional adapter or extension. So one additional 10 gauge extension cord is allowed as long as no other adapters are used. It is a standard RV 120 volt 30 amp system.
The TT came with a 25 foot 10 gauge cord. I bought a 25 foot extension with 30 amp plug and socket so no adapters were needed. I frequently camp at state and federal campgrounds in Wisconsin and occasionally in Texas. I have never needed the extension. It is still in shinny new condition. A 30 foot or longer TT may occasionally benefit from an extension for rear or "wrong" side pedestal connections.
Extending shore power connections requires consideration for current draw and distance. Tables and rules of thumb are often used to determine what works. The "one adapter or extension" is a rule of thumb. The definitive test is measuring the voltage at the TT appliance while the full desired load is working.
A cheap $15 voltmeter is all that is required. First measure the voltage at the shore power outlet. Desired voltage is 120 volts. It may be lower. That makes things more complected.
Connect the extension cord. Turn on high power appliances like A/C, water heater, electric refrigerator, etc. Remember, these things start and stop automatically and must be "on" for this test. Measure voltage at an outlet inside the TT. The minimum voltage for many air conditioners is 108 volts. It is desirable to have higher voltage.
Power management may be required. Switch water heater and/or refrigerator to propane to reduce load. Remember a microwave is also a high power device. You may not be able to run more than two high power devices even without the extension cord. If shore power voltage is lower (summer heat wave in Fla.) Fewer devices may be required. Voltages below 108 volts at the pedestal has been reported. Keep voltage in TT above 108 volts. Reduce usage as required.
I bought a 25 foot sewer hose for dumping tanks. I frequently dump at campground dump stations in Wisconsin. 25 feet was excessive and clumsy. I bought a 10 foot replacement (6ft when compressed). It works much better.
I installed a belly mounted sewer hose holder for the second hose. Keeping the "stinky slinky" out of my storage compartments is desired.
In Texas, many campsites have a dedicated sewer drain. The 25 foot sewer hose was useful for rear of site drains. Some people find a sewer hose support device useful to get good flow over longer distances.
I wish you good luck and happy trails ahead!