The overtaker must assess their options - be able to visually check their path, assess power of their vehicle, their confidence level, condition of the road, wind, speed/distance of the other vehicles. Then they make a judgement call and take the risk or don't take the risk.
The vehicle being overtaken must by law allow space between themselves and other vehicles so the overtaker can pull back into the lane safely. Thus, give them room if they need it! The overtaken must stay in their lane and not increase speed. All the vehicle being overtaken needs to do is not change the situation and never put themselves or the overtaking vehicle in a predicament that could end badly for all.
It is not advisable that a slow vehicle drop wheels off the road shoulder to allow a vehicle to overtake, especially in a caravan or towing trailers unless they truly believe there is no risk. Gravel road shoulders and deteriorating bitumen edges can be exceptionally dangerous to any vehicle but even more so to someone towing a trailer. Please don't move over because you feel pressured, only do so because you feel safe to do so. All the risk of overtaking lays with the overtaking vehicle and maybe they simply need to wait until the road straightens or widens or you come upon an overtaking lane, at which time you could slow down and allow all those following you a chance to get past you.
It should never be a problem if all road users respect each other and remember that every person has a right to go about their business and do so safely. Even slow caravans, even truck drivers, even other passenger vehicles driving to/for work, or to pick up children or going on holidays.