I feel your pain. My DDs are 12 months apart. I am happy to say that it does get easier (they are now 6 and 7
The best thing I did was put toys away and bring them out at different times. So I had a big plastic tub with all the blocks, one with little people, one with babies etc. When they got bored of playing with these I put the one tub away, waited a while and then "found" another tub. I know it is an old suggestion but it is a good one.
About this age I also saw a phychologist who gave me good suggestions about scheduling. Plan like a daycafre centre and that it is ok to plan both some tv time and some free play (I know tv is frowned upon for under 2s and I was always one of those advocates until I had two so close in age and a bit of tv was all that got me through the 4.30 crazy time).
Your ideas sound good.
I remember how shops were hard.
We used to do
Morning play usually at the park
Playtime (outside - water, sandpit, push carts etc)
Inside play cause it was so hot (with one of those magical boxes)
Then either outside or park or me walking them in the pram
I liked outside as much as I could cause I don't cope very well with messy inside toys
Just remember you don't have to keep them "entertained" all the time.
Plus can they help you with pegs? Sweeping? Pushing the washing trolley etc?