Where are you located
@cdpm ? I'm just asking because your location might influence the advise people give
I don't think one meal a day is recommended now, but I understand your difficulties. Variety in the diet is to try and ensure that you get all the nutrients you need. Variety is also to minimise the risk of getting too much of what is harmless in small or "normal" amounts but might be harmful if you ate it every day (e.g. by adding variety to the diet you mitigate or eliminate the risk of, say, consuming too many heavy metals by eating the same thing every meal every day). The three sides of the triangle are generally given as variety, moderation and balance. But I understand that with low finances, intolerances, dental issues, needle tip issues etc this might be tricky
Are you able to tolerate berries, and are they ok for your blood sugars and budget? In-season produce is usually cheaper at the supermarket and if you buy what's in season not only is it cheaper but you get variety. Are berry or fruit smoothies an option?