Just opinions: Find someone fairly close to you who has the fruit that you are talking about and ask about varieties that are the best fit. My guess is that you are talking about apples but maybe not. All that is written about good fit and disease resistance is not 100% and varied in the local environment. Even the old heirloom varieties have environmental limits that you don't know about until you try them. Point - you will not be able to select 3 or X number of varieties on these grafted trees that really work in your area.
Deer? The trees come fairly small. If variety 1 and 2 are on lower limbs and you have deer pressure those limbs are going to be worthless to you unless you fence for deer control. Otherwise the lowest fruit you ever pick will be at about 4' high. I have multiple species on trees but I grafted into larger trees for either keeping new varieties around to watch or needed to take out a tree and wanted to save the variety here.
Heirloom varieties: Some are great and there are reasons why many are not grown today. They were from given environments and I have found many to be unable to live here because of that. But when you find the ones that work - BINGO! It just takes trial, time and willingness to cull.
Recommendation: Same folks who help you locally on varieties - ask them about the best semi-dwarf rootstocks for your soil and disease pressure. Get two or three of the best varieties for your area on their own rootstock and train the trees to be normal in whatever pattern of scaffold limbs you want. Top them when they get too tall for your safety or your ladder. If you have no one to ask there is info on rootstocks, soil types, ... but it takes more time. If no one to ask, don't try varieties from colder climates if that is where they thrive, were discovered or were grown historically. Soft fruits, like peaches, plums, ... - the commercial growers have better fungicides, insecticides and "stuff" that you will use. Same deal: find species that have some resistance if you can.