Got near a hundred mini watermelon this year, the very late ones were no good but for a couple months they were glorious. Mini love variety, it was a brutally hot summer and they flourished, I let them take over the whole garden.
Two plants survived being overrun by watermelon, the asparagus and the hong tsoi. I'm sort of resting it until "spring" which is planted around Feb here.
Piel de sapo (Toad Skin) is from the arid regions of Spain. Commonly grown in the Almeria region under greenhouses. The old OP variety is susceptible to just about everything. Some of the newer varieties are more disease resistant. They are 100% grafted in Spain because of widespread MNSV in the soil. So they have some pretty shitty root systems.
https://en.wikipedia.org/wiki/Melon_necrotic_spot_virus
You might have better luck with a canaries melon. They are often grown in tropical regions and tend to be a bit more resistant to fungal diseases.
If you have severe cucumber or squash beetle infestation, look into some netting. Of course under netting fungal diseases are much worse.