Some rackets lend themselves to easy customization, others never feel right no matter what you do.
Take the PS95 for example - great feeling graphite/kevlar braid, superb drill pattern but feeble in terms of mass and swingweight. By the time you'd fiddled about with it to get the weight 'about right' and the racquet stable, you're in the 350-360g range and have just wasted weeks/months of time playtesting, adjusting, playtesting adjusting etc. The Tecnifibre 315 Ltd is another flexy, underweight lemon.
That Ultra Tour, I suspect is going to need alot of lead in the hoop. Then you're probably going to need weight in the handle to counterbalance, probably some in the throat as well to balance the distribution of weight, with huge amounts of time experimenting and adjusting. Underweight 305g 20mm thin beamed rackets are high maintenance and a huge time drain in terms of customization. Throw in Wilson's extremely poor manufacturing variations and the whole thing is just an exercise in frustration.
If you want a good 18x20, get a 6.1, old Prestige MP, or the Blade 98. Wilson have been producing quite a few SNAFUs in recent years and I suspect that this will also fall into that category.