Wishful thinking I know and no cost spared!
Lets assume that good weather, good toilets and showers are a given!
In no particular order other ideas;
For me a good show needs a rural setting and be far enough away from homes not to disturb anyone and yet good access expecially for MV's of all shapes and sizes.
When the public attend in their cars they need to be able to park first and pay later, as a kiosk a few paces from the road will create a mother of all traffic jams, and this will putting people off from coming back next year.
Free entry for exhibitors and a welcome pack perhaps with a voucher for discounts or complimentary item.
IMHO fun fares should be removed from MV shows as I don't think they go with such events! Perhaps I'm getting old but they never seem to be so essential to even the most bored kid in town! The space taken should be occupied by loads of food vendors to give a bit more choice and of course the beer tent far enough away from the camping area so as not to disturb those who like to go to bed early especially on the last night as they have a 300 mile drive home in the morning!
For the arena this needs to be a grass covered arena with woods on one or more sides and big enough so that the Axis forces could crash out of the woods far off in to the distance and advance towards the Allied Forces near the crowd, as apposed to the battle being confined to half a football pitch.
Apart from arena events staged with MVs and re-enactors thought should be given to marching military bands perhaps in a small arena with band stand seating. Perhaps this could be staged later in the evening in a setting that could be lit by searchlight or film type lighting. Who remembers Wembley Stadium Military Band Extravaganzas?
As for the MVs I hate these being parked so close together you cannot photogragh them and equally I don't like it when owners put up an enormous history display board in front of or on their MV to and get arsey if ask to move it for one quick photo. One show i went to many years ago had the vehicles entering the arena along a track next to a hedge with a barrier down the public side of the track which allowed perfect photos to be taken without things in the back ground to distract from the shot. So a good spacing for MVs is essential .
I do like green camping but often the interpretation of this gets a bit blurred with civi style green camo tents out of keeping with the vehicles age. Still this is better than portaloos, white van and civi tentage surrounding an MV to such extent that a military vehicle enthusiast feels too intimidated to get near the MV as they feel they are intruding in to someones living space.
Apart from numerous stalls, it would be good to encourage owners of vehicle collections such as Wheatcroft to display a section of vehicles in a static park or for museums etc to have tents to show off their exhibits. With 2020 being the 75th anniversary of the end of WW2, it would been great to see an exhibition of vehicles, uniforms and equipment of the Britsh Army as at Sept 1939 and again as at 1945, and possibly so for German Forces too, so as to see how much changed in a few short years; Matilda Mk I compared to a Comet tank?
Going back to arena events it would be good to perhaps make use of those large RC aircraft and perhaps make some kind of choreographed aerial attack on RC tanks perhaps with a bit of pyrotechnics thrown in too. Combining RC aircraft with shot gun 'flak' has been done and might look good but may endanger the public when the RC planes crash and burn! On a similar destructive theme every young boy and his dad loves destroying things so an air rifle range to shoot at and stop moving RC tanks being driven over an undulating terrain by someone else might be a great hit with the mostly male public. Driven in and out of 'cover' a 1/16th scale RC tank is still hard to hit 25 metres away!
More suggestions to follow!