Liquid oral is just fine as it's very convenient but due to the alcohol it taste like shit. For filler when capping, you can use creatine, glutamine, dextrose etc. It'll take about 10min to cap 50 pills using a $25 capping machine.
That recipe you posted will work, you could even make it without the peg but imo it'll taste so fucking bad. Just remember that you'll have to shake the bottle up every time you draw to make sure mg per ml is consistant.