Applying 5 year visitor visa for parents. Proving home ties.

Please may I have advice on my query about getting 5 year visitor visa for parents?
My parents have held a number of (about seven) 6 month visitor visas and one 2 year long term visa. Have not been able to hold visas or visit UK since Oct 2019 due to subsequent travel restrictions. I am their only child (now a British citizen, employed etc.), I have been living with my spouse and child in the UK for over 10 years, and my parents have all their property, income and their social lives in the home country and they have no intention to make UK their main home except they spend a couple of months a year in the UK. The reason for applying a long term visa is to reduce the hassle of dealing with the processes in the current climate.
Please could you advice how I should approach the ties to home country if they apply for a long term visa, as in this case the only child lives in the UK (I don’t want the visa office to doubt my parents’ stays unfairly, just because their only child lives in the UK). All my extended family (aunts, in laws) lives back home. I would very much appreciate and value your advice on 1) the chances of been granted a 5 years visa 2) if chances are good, then how best to prove home ties? Are there anyone in the forum who had previous success in getting 5 year visas or even 10yr visas for parents? Appreciate your advice/experience. Thank you very much.