I am still working on a similar idea but use a nuclear reactor instead that runs with only 7 components at 40 EU/t. Since a miner roughly uses 20 EU/t this would allow to power 2 miners (including pumps). So you would have to carry around the reactor + components, the mining setup including a LV converter, cables and a MFE for a total of 22 item slots. If you take some tools with you, that still leaves enough slots to even carry around Macerators/Furnaces to immediately convert the resources found. Add a compressor and you have your infinite, portable mining setup.
The question however is how to carry the resources you find?
i'd still advise you to use two geothermals instead. if you place the pump next to the miner and the geothermals next to the pump the pump will pump directly into them, without needing any cells. if you put cells into the pump to get the surplus lava, the pump will prefer to fill the geothermals before it fills cells. with geothermals you actually wouldn't need any kind of energy storage, since they stop automaticly when no one needs energy.
my experience also tells me that lava also quite offen prevents you from finding the neet resources below it, you can miss quite a lot of diamonds because of that.
with that said i think it's worth to use geothermals and to invest into an automatic empty cell refilling complex for a mining platform.