Initial Problems
As a UK citizen, one assumes that any problems can be solved as in the UK however a number of issues rise to the surface. Not insurmountable but it just takes a little while, not to say patience, to get ones head around them all at once.
Purchasing the RV
Firstly one should be aware that only three States do not charge a sales tax. Even though the RV was a private purchase it is when you register the vehicle that the tax becomes due. Oregon and Wyoming do not exercise a sales tax therefore ensure, if possible, that you establish a domicile address in those States, or when you register the vehicle and or pay the vehicle tax you will find a nasty bill waiting for you from the State Government.
Insurance
Any Foreign National wanting to insure their vehicle will need a USA Drivers Licence, an International Licence will not suffice. Having said that taking the test is probably one of the easiest you will ever encounter, big worry there as well as it means that anyone who is not blind can get one as well, and they do. You will need your passport and an additional supporting form of documentation. Get the printed information from the State Driving Licence Office and read carefully, do not assume that the officials know what is required, as you probably are the first foreigner they have encountered taking a test.
Driving
Having got the Drivers Licence and Insured the vehicle, driving the RV is not that difficult. in fact given the size of the vehicle it is remarkably easy with power steering, automatic gearbox, very powerful engine and anti-lock brakes. Given that the roads, for the most part, are wide and even in the cities the lanes are more than ample. The main issues concern other drivers, cutting corners at junctions are de rigor in the USA, as well as no turn signals, or if done it is purely accidental as their hand caught the indicator stick as the wheel was turned. See (Additions & Alterations to the RV Section)
The only issue I have had problems with is negotiating the ramps on and off the roads at petrol stations and shopping centres. Do not attempt to negotiate them straight on, but at an angle or you may find the back of the RV grounding at the rear leaving you with the embarrassment of being suspended with no drive to the rear wheels, as well as an expensive bill.
The only other tip I can offer is to leave a very generous distance between the vehicle in front as braking suddenly may cause the driver behind to take their eyes of the keypad of their mobile phone when texting or cause an to late interruption to their highly engaging discussion they are having. Rear end collisions are legend in the USA.
Whilst on the subject of driving techniques the previous owner of my RV got 8.5 mpg from it. I am averaging 12.5 mpg. This increase is purely due to advance reading of the road ahead. that is to say the a 6.5 ton (unloaded) vehicle has a large momentum and will coast for a long way without loosing any great speed between lights. I once had a driver pull alongside me in Spokane and told me that my brake lights were not working! When I responded that I had not used them he was totally bemused.