"Might get rid of that ice-shell by have a multi-layer refelctor system, and some very low heat-transfer material between payload and shield. If 99% of the incoming light can be reflected then the first layer of the shield is at 1827 K. Add reflectors and insulation to get it down to something you can handle."

Your incoming light is more than light, it's infrared, x-rays, ultra-violet, ect. I doubt you could reflect 99% of it. Nor are you going to radiate the heat into half your sky which is 5800 K.
I wonder if you reflect 90% of the energy, and also doubt if you absorb more than 90% [assuming you want it].

I think insulating anything would be a big mistake, my worry is if you can conduct the energy fast enough away from it- assuming it's reflective. So I was thinking you would "refrigerated" it pumping lot water vapor through pipes before it exits as rocket propellent. Ablative shielding might also be problem at such high velocities- it could creating an atmosphere and any atmosphere even if you are creating it might be something you want to avoid.
Though perhaps, creating an atmosphere if done right could be helpful.

"Masses less than an ablative ice-barrier.

Well I wasn't thinking of launching such thing from Earth, and there shouldn't be any shortage of ice on Europa.

"And easier system might be the beryllium balloon sail that Matloff et.al. posted to the arXiv. Only have to dip into ~0.1 AU or so, so somewhat easier thermal environment, and you leave at ~400 km/s."

Well, instead deploying 14 million km from the Sun, could you deploy it about 5 million km from the Sun going about 500 km per sec away from it?

"BTW- The sublimation energy of ice in a vacuum is ~0.45 eV per molecule, or about 2.4 MJ/kg. At 63.08 MW/m^2 it's about 26 kg/s sublimed away, or roughly an inch a second. Ice/water (under pressure) absorbs about 3 MJ/kg before it becomes steam and is then really difficult to handle. But it absorbs different frequencies in different ways. To IR liquid water is a blackbody, but semi-transparent to visible light... etc."

I wonder if the water exhaust would sort of explode after leaving a rocket nozzle with that intense solar radiation close to the Sun.